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The Patient-Specific Index: Asking Patients What They Want*

JAMES G. WRIGHT, M.D., M.P.H., F.R.C.S.(C) and NANCY L. YOUNG, B.SC.P.T., M.SC., TORONTO, ONTARIO, CANADA

Investigation performed at the Departments of Surgery, Physical Therapy, Clinical Epidemiology, Preventive Medicine, and Biostatistics, University of Toronto, Toronto

	Abstract

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The Patient-Specific Index is used to assess the outcome of total hip arthroplasty by evaluating the preferences of the individual patient. The purpose of this study was to determine the reliability, validity, and responsiveness of this index and to compare different methods of combining patients' ratings of the severity and importance of their complaints, to obtain Patient-Specific Index summary scores. All patients who were scheduled to have a total hip arthroplasty performed by one surgeon at a single institution were eligible for the study. The patients completed the Harris hip score form, the McMaster-Toronto Arthritis (MACTAR) Patient Preference Disability Questionnaire, the Short Form-36, the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and the Patient-Specific Index. With use of the Patient-Specific Index, patients rated the severity and importance of each complaint. These ratings were summed in four different ways to derive severity-importance scores. The questionnaires were completed twice (two weeks apart) before the total hip arthroplasty and twice (two weeks apart) six months after the total hip arthroplasty by a subset of the patients. The seventy-eight participating patients had a mean age of 62.2 years (range, twenty-five to eighty-seven years) at the time of the operation. Forty-three patients (55 per cent) were men, and sixty-three (81 per cent) had osteoarthrosis. The inter-rater and intra-rater test-retest random-effects intraclass correlation coefficients of the Patient-Specific Index were 0.77 or greater (greater than 0.75 is considered excellent). Construct validity was shown by correlations of the Patient-Specific Index with other scales. The additive versions of the Patient-Specific Index (with a responsiveness statistic of 3.3 or greater and a standardized response mean of 1.6 or greater) were more responsive than the other scales. We concluded that the Patient-Specific Index is reliable, valid, and responsive. The additive versions were the most responsive and are recommended for future applications. Such indices need to be tested in studies of patients who have osteoarthrosis of the hip and other musculoskeletal diseases, to ensure generalizability of the results.

	Introduction

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The primary goals of total hip arthroplasty are relief of pain and improvement of function^33,43,53. Many different measures of outcome (so-called hip-rating scales) have been developed to quantify patients' complaints. The scales have a similar format, with patients rating the severity of the pain and disability on a list of specified complaints. Each complaint has an arbitrary point score, or weight, assigned by the clinicians who originally developed the scale. When the scores are summed across complaints within each subscale, the results indicate the degree of dysfunction of the hip. A change in the patient's status, when calculated on the basis of the difference between scores before and after the total hip arthroplasty, is an indication of effectiveness.

The hip scales that are currently in use are associated with several problems. First, because no scale has demonstrated clear superiority, a daunting array of scales have been used, making comparisons between trials extremely difficult^24,25. Second, most of the existing scales have not been thoroughly tested for reliability and validity^26,27. Third, clinicians differ in their opinions regarding which symptoms to include in a scale and how to rate their relative importance. Because ratings differ substantially according to the scale used, the assessment of the results of total hip arthroplasty may be affected by the scale with which they are rated^2,12. Finally, patients' opinions were not incorporated into the development of the existing scales of which we are aware nor have patients' preferences for the relief of complaints been considered. For all of these reasons, many of the existing scales may not be valid from either the surgeon's or the patient's perspective.

Orthopaedic surgeons tend to rate the outcome of total hip arthroplasty higher than their patients do⁴⁸. Moreover, failure to consider individual complaints may cause clinicians to rate a hip replacement as successful in patients who are disappointed because the complaints that they considered the most important were not alleviated. Asking patients what they want to see improved by a total hip arthroplasty can affect the content and the relative weighting of the questions in a scale⁶⁹. For example, preoperative complaints, such as nighttime pain, limb-length inequality, fear of falling, and restrictions in recreational and sexual activities, are not addressed in most of the current hip-rating scales⁶⁹. Furthermore, because the frequency of the complaints and the importance attached to their relief vary among patients, these variables should be considered in the assignment of the point score (or weight) assigned to each complaint. For example, only twenty-three (32 per cent) of seventy-two elderly patients reported that osteoarthrosis of the hip interfered with sexual activity, but for these patients relief of this difficulty was extremely important⁶⁹. Thus, asking individual patients what they want may substantially affect the construction of a scale.

Formal evaluation of patient preferences for relief of complaints is particularly relevant to orthopaedic operations because most elective procedures are performed to relieve pain and functional disability. A standardized method that incorporates the preferences of individual patients for the relief of complaints would have broad application to the evaluation of many operative procedures intended to improve functional disability. The Patient-Specific Index allows patients to indicate the type, severity, and importance of their complaints⁶⁹. The purpose of the current study was to determine the reliability, validity, and responsiveness of the Patient-Specific Index and to compare different methods of combining patients' ratings of severity and importance in order to obtain Patient-Specific Index summary scores.

	Materials and Methods

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Sequential patients who were scheduled to have an elective primary or revision total hip arthroplasty between July 1992 and April 1993 were considered for enrollment in the study. Patients who could not speak English or who were to have a total hip arthroplasty as part of a reconstruction for a tumor, an acute fracture, or an infection at the site of a total hip arthroplasty were excluded.

All patients had the total hip arthroplasty at St. Michael's Hospital, Toronto, performed by the same surgeon, with use of the same operative approach and a consistent perioperative course. This approach was used to minimize the effect of multiple variables on the outcome of total hip arthroplasty. Prostheses that were inserted with cement were of the Contemporary design, while those inserted without cement were of the St. Michael's design (both manufactured by Howmedica, Guelph, Ontario, Canada).

The patients were evaluated both before and six months after the total hip arthroplasty. The patients were allowed to review their previous responses at the six-month assessment²⁹. All patients were questioned regarding demographic information, diagnosis, previous hip disease, and previous operative and non-operative treatment. The interviewer administered five questionnaires, in random order; these included the Harris hip score, the McMaster-Toronto Arthritis (MACTAR) Patient Preference Disability Questionnaire, the Short Form-36, the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and the Patient-Specific Index. A user's guide was constructed to ensure that the questionnaires were administered with use of the same language. (This guide may be obtained by writing to one of us [J. G. W.].) Furthermore, standard prompts were used to maintain consistency for patients who did not understand the questions.

We evaluated the reliability, validity, and responsiveness of the Patient-Specific Index. A measure is considered reliable if the same result is obtained when the evaluation is repeated on different occasions by the same or by a different observer, and a measure is considered valid (or accurate) if the attribute of interest is measured correctly⁶⁸. The final criterion for the evaluation of a scale intended to measure change is its responsiveness (or sensitivity) to clinically important change^{16,17,28,31,45}.

Scales
The Harris hip score is a 100-point scale for the rating of pain (maximum, 44 points), function (maximum, 47 points), range of motion (maximum, 5 points), and absence of deformity (maximum, 4 points)³². The reliability and validity of the Harris hip score, which is one of the most commonly used hip-rating scales, are unknown.

The McMaster-Toronto Arthritis Patient Preference Disability Questionnaire is a reliable, valid scale⁶¹. Patients list their symptoms and rank them in the order that they would most prefer to have them alleviated by treatment. Only the five most important symptoms (also called signal measurements) are rated, before and after treatment. This questionnaire demonstrated superior responsiveness in a randomized placebo-controlled trial of methotrexate in patients who had rheumatoid arthritis^10,61,63.

The Western Ontario and McMaster University Osteoarthritis Index was developed to evaluate patients who had osteoarthrosis of the hip or the knee. The index contains three subscales: one for pain (five items), one for stiffness (two items), and one for disability (seventeen items). This questionnaire can be self-administered, and it is reliable and valid^5-8. Responsiveness was demonstrated in a randomized, controlled trial of non-steroidal anti-inflammatory drugs for the treatment of osteoarthrosis⁹.

The Short Form-36 is a commonly used, reliable, and valid generic health-status measure with eight subscales. These include physical function; role limitations due to physical health; role limitations due to emotional problems; vitality, energy, and fatigue; mental health; social functioning; bodily pain; and general health^50,60,64.

The Patient-Specific Index is intended to evaluate the complaints of individual patients before and after total hip arthroplasty⁶⁹. Patients rate twenty-two complaints (and any additional ones) for severity and importance (Appendix). These complaints were selected from seven previously published scales^{13,35,39,42,46,51,58} and were identified on the basis of interviews with seventy-two patients⁶⁹. Severity was defined as the degree of the complaint, such as extreme difficulty with stair-climbing, and importance was defined as the level of concern that the patient had about the complaint. For example, although a patient may have extreme difficulty with stair-climbing, this activity may be of minimum importance to the patient if there are no stairs in the residence. The severity of each complaint was rated according to seven response categories, which depended on the question. The importance of relief of the complaint also was rated according to seven categories, which ranged from "not important at all" to "extremely important." (Although visual-analog scales were used to rate importance for the Patient-Specific Index in the previous study⁶⁹, ordinal rating scales are easier for patients to use and provide similar precision³⁰.) The patients' ratings of severity (S_i) and importance (I_i) for each complaint were multiplied together (S_i X I_i), and these products were summed across all complaints to yield the multiplicative cumulative Patient-Specific Index score (xxxx [S_i X I_i]). A total possible score was then calculated as the sum of the importance ratings (I_i) multiplied by the maximum severity score (S_M) for each complaint (xxxx [S_M X I_i]). The ratio of the sum of the patients' severity-importance products divided by the maximum score (100 X xxxx [S_i X I_i]/xxxx [S_M X I_i]) forms a percentile score ranging from 0 to 100, with 0 indicating the worst rating and 100, the best.

View larger version (56K): [in this window] [in a new window]   Appendix - Patient-Specific Index

Intra-Rater and Inter-Rater Reliability
In order to determine test-retest reliability, thirty patients were interviewed twice (two weeks apart) before the total hip arthroplasty. The interval of two weeks was chosen because the clinical status of the patients was not expected to change substantially during this time and the chance of patients recalling their previous responses was minimized. Fifteen of the first preoperative interviews were conducted by the same interviewer, and fifteen were conducted by a second interviewer to allow the determination of both inter-rater and intra-rater reliability of the scales. Thirty patients also were interviewed on two occasions, separated by two weeks, six months after the total hip arthroplasty: fifteen, by the same interviewer, and fifteen, by a different interviewer. Both groups of patients were included in the reliability testing so that the reliability coefficient would not exclusively reflect the reliability of the preoperative assessments.

The sample-size calculation for test-retest reliability was based on the random-effects intraclass correlation coefficient^3,59. The intraclass correlation coefficient (ranging between 0 and 1) is an index of concordance for continuous data. An intraclass correlation coefficient of less than 0.4 is considered poor; between 0.4 and 0.75, fair; and greater than 0.75, excellent⁵⁷. On the basis of a projected reliability coefficient of 0.8 or greater and an intent to detect an intraclass correlation coefficient of at least 0.6 with an alpha of 0.05, a beta of 0.20, and two measurements per subject, approximately thirty patients were required^18,19. Although the measurements obtained with use of hip-rating scales are more likely to be ordinal than continuous, the intraclass correlation coefficient is easier to use with large data sets and yields the same results as the quadratically weighted kappa used for ordinal data²².

Validity
Construct validity was established by theorizing relationships between scales and then evaluating the a priori hypotheses^15,54. The construct validity of the Patient-Specific Index was evaluated by comparing the Patient-Specific Index scores with those of the Harris hip score, the Western Ontario and McMaster University Osteoarthritis Index, the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire, and the Short Form-36 (Spearman correlation). Our a priori hypotheses were that the Patient-Specific Index would show the highest correlations with the pain and disability subscales of the Western Ontario and McMaster University Osteoarthritis Index; moderate correlations with the Harris hip score, the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire, and the pain and physical function subscales of the Short Form-36; and the lowest correlations with the other subscales of the Short Form-36.

For the analysis of validity, the sample-size calculation was based on correlation analysis. To demonstrate a correlation of 0.7 with an alpha of 0.05 and a beta of 0.20, fourteen patients were required⁴¹.

Responsiveness
Responsiveness was evaluated by measuring the change in the patient's status after the total hip arthroplasty (a treatment of known efficacy). Responsiveness was quantified for each of the five scales with use of the standardized response mean and the responsiveness statistic. The standardized response mean is the mean change in the score divided by the standard deviation of the changed score³⁷. The responsiveness statistic quantitates the amount of change as a ratio of the variability in the stable state. The responsiveness statistic is calculated²⁸ as the ratio of the clinical change after a known therapeutic intervention () divided by the variability in test scores for stable subjects (2MSE).

To detect a moderate effect-size⁴⁰ difference of five units with a power of 90 per cent and a two-tailed alpha of 0.05, a standard deviation⁶⁹ of 11.0, and an estimated correlation between scales of 0.3, fifty patients were required.

	Results

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One hundred and thirteen patients had a total hip arthroplasty between July 1992 and April 1993 and were considered for enrollment in the study. Of these 113 patients, seventeen were excluded: ten, because they were not scheduled to return for follow-up, and seven, because they were unable to complete the questionnaire (four, because of difficulties with the language, and three, because of impaired mental function). Of the ninety-six eligible subjects, five had a change in the time of the operation that prevented preoperative assessment, one was totally asymptomatic (revision was performed because of migration of the acetabular component), and eight refused to consent to the study; this yielded an enrollment of eighty-two (85 per cent) of the eligible subjects. Of these eighty-two patients, seventy-eight (95 per cent) completed the study. Of the remaining four patients, three died within six months after the operation because of unrelated causes and one was lost to follow-up.

The mean age of the seventy-eight enrolled patients at the time of the operation was 62.2 years (range, twenty-five to eighty-seven years). Forty-three patients (55 per cent) were men, and sixty (77 per cent) had a primary total hip arthroplasty. The mean age of the thirty-five patients who were excluded from the study was 53.5 years; thirteen (37 per cent) were men, and twenty-six (74 per cent) had a primary total hip arthroplasty. Of the seventy-eight enrolled patients, fifty-six (72 per cent) had idiopathic osteoarthrosis, seven (9 per cent) had avascular necrosis of the hip, seven (9 per cent) had osteoarthrosis due to childhood hip disease, five (6 per cent) had rheumatoid arthritis, and three (4 per cent) had other diagnoses. Fifty-eight patients (74 per cent) had involvement of other joints in the spine or in the upper or lower extremities. Fourteen patients (18 per cent) reported that they had completed primary school; thirty-two (41 per cent), high school; nine (12 per cent), college; seventeen (22 per cent), university; and six (8 per cent), postgraduate school.

It took the patients a mean (and standard deviation) of 16.0 ± 5.5 minutes (range, three to thirty-five minutes) to complete the Patient-Specific Index, 8.5 ± 2.8 minutes (range, four to fourteen minutes) to complete the Short Form-36, 2.9 ± 1.8 minutes (range, one to nine minutes) to complete the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire, 8.1 ± 2.8 minutes (range, two to eighteen minutes) to complete the Harris hip score, and 6.6 ± 2.8 minutes (range, two to eighteen minutes) to complete the Western Ontario and McMaster University Osteoarthritis Index.

The most severe complaints before the operation were difficulty with public transportation, unequal limb lengths, concern about falling, the need to use walking aids, and difficulty with recreational activities (Table I). The most important complaints were difficulty with walking, daytime pain, and loss of independence (Table I). The importance ratings were not always related to the severity ratings. For example, difficulty with public transportation was given a high preoperative mean severity rating of 6.3 but a low importance rating of 2.7. The highest preoperative mean severity-importance products were those for difficulty with recreational activities, difficulty with walking, and loss of independence.

All methods of combining the ratings for severity and importance resulted in intraclass correlation coefficients of 0.77 or greater, indicating excellent agreement (Table II). Thus, all four versions of the Patient-Specific Index had satisfactory intra-rater and inter-rater reliability.

	Discussion

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The recently renewed emphasis on evaluating the functional outcomes of medical and operative treatment⁶² has been accompanied by admonitions that the patient's preferences should be incorporated into the assessment^{1,20,21,44,65,66}; however, relatively little attention has been directed toward the development of practical and standard methods of accomplishing this. The problem is particularly pertinent when the primary purpose of the treatment is to relieve pain or to decrease functional disability. If the patient's main goals are not clearly determined and specified, the therapeutic accomplishments may be appraised with use of the wrong target. The clinician may be satisfied with the achievement but the patient may remain dissatisfied.

The Patient-Specific Index allows patients to indicate the type, severity, and importance of their complaints. Furthermore, it includes complaints that are important to patients, many of which have not been incorporated into previous scales. A complete evaluation of a scale, however, requires documentation of reliability; validity; and, if appropriate, responsiveness^21,37,40,62.

Reliability is the basic requirement of all scientific measurement^54,68. Regardless of how the Patient-Specific Index was aggregated, it had excellent reliability. The second requirement of a scientific measurement is validity. Because the items included in the Patient-Specific Index were derived from seven previous hip-rating scales, interviews with clinicians, and interviews with more than seventy patients, the Patient-Specific Index has both face and content validity. Criterion validity is established by comparison of a measure with a so-called gold standard⁵⁴. Because no such standard exists for measures of functional disability, construct validity was established by theorizing a priori relationships between the Patient-Specific Index and scales intended to measure similar phenomena⁵⁴. The Patient-Specific Index was shown to be valid by the strong correlations with other scales, confirming our a priori hypotheses.

The Patient-Specific Index also was shown to be as responsive as or more responsive than the other types of scales used in this study. Although the Patient-Specific Index took longer to complete than the other scales, this increase in time probably would be offset by the need for a smaller sample size because the use of a more responsive measure of outcome in a clinical trial reduces the number of patients required to demonstrate a clinically significant difference between two treatments⁶¹.

Responsive scales have several advantages. First, although numerous hip-rating scales have demonstrated that patients are substantially better off postoperatively³³, improved measures of outcome may be required to determine which of the many available procedures for total hip arthroplasty is preferred for relieving symptoms that are important to patients^33,43. Second, more responsive measures would show a greater incremental effectiveness for the same cost and thus a more favorable cost-effectiveness ratio⁴⁷.

The Patient-Specific Index also provided useful information on how patients' complaints decreased after total hip arthroplasty. On the average, the severity-importance products improved for practically all complaints. Despite a substantial reduction in most physical disabilities, patients continued to have difficulty with bathing, public transportation, and sexual activity. This information may be useful for providing patients with reasonable expectations of the functional improvements after the operation. Furthermore, despite the infrequent attention to recreational activities in the existing hip-rating scales^14,34,38, the highest mean severity-importance product for patients before and after the operation was difficulty with recreational activities. This suggests that recreational activities should probably be included in any evaluation of the results of total hip arthroplasty and that patients should be counselled with regard to the anticipated outcomes in this area.

The outcome of total hip arthroplasty may be assessed with many different types of scales. Health-measurement scales may be classified either as generic health-status measures or as disease-specific measures⁵⁶. Disease-specific measures, such as the Patient-Specific Index, the Harris hip score, the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire, and the Western Ontario and McMaster University Osteoarthritis Index, focus on particular complaints attributable to the disease or the condition. Generic health-status measures, such as the Short Form-36, are intended to measure all aspects of a patient's health, including not only physical function (the focus of most hip-rating scales) but also emotional, mental, and social function. The current study confirms that disease-specific scales, such as the Patient-Specific Index, are more responsive than generic health-status measures for evaluation of the outcomes of orthopaedic procedures^11,36,49,51. However, because general health-status measures such as the Short Form-36 are comparable across different diagnostic groups and focus on all aspects of health, a complete evaluation of an operative treatment such as hip arthroplasty probably requires the use of both a specific and a generic questionnaire^11,67.

Some types of disease-specific scales, such as the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire and the Patient-Specific Index, focus on the complaints of individual patients. The former scale, however, has two potential disadvantages. First, the patient rates only the five most important complaints. Second, the weighting scheme for the complaints is arbitrary (the most important complaint is weighted as 5 points, and the least important is rated as 1 point). (O'Boyle et al. described a method of evaluating the quality of life for individual patients, called the Schedule of Individual Quality of Life⁵⁵. Although this method highlighted the importance of individual preferences, it also restricted patients to five complaints and required them to rate twenty profiles. Thus, the Schedule of Individual Quality of Life is less feasible in routine clinical practice.) The Patient-Specific Index allows the patient to rate all complaints, not just the five most important ones. Furthermore, the patient's importance ratings are used to weight the complaints rather than the weights being arbitrarily assigned.

The multiplicative percentile Patient-Specific Index, as originally described⁶⁹, had three disadvantages. First, two aspects of the original Patient-Specific Index—multiplying the severity and importance ratings for each complaint and deriving a percentile score by dividing the score by the maximum possible score—were somewhat arbitrary. Second, this method was somewhat complicated to use. Finally, and perhaps more importantly, dividing by the maximum possible score was based on an assumption that patients who had multiple complaints were as disabled as those who had few complaints. Recent research, however, suggests that the number of symptoms is related to patients' perceptions of ill health²³. A method that simply sums the importance and severity scores without deriving a percentile score addresses these problems. First, summing patients' ratings of the severity and importance of their complaints is simpler. Second, the high correlations between the number of complaints and all measures of disability suggest that patients who have more complaints are more disabled, which is reflected better with use of a non-percentile method. Finally, the additive cumulative version of combining patients' ratings of severity and importance is among the most responsive versions of the Patient-Specific Index. Although the additive percentile version is not as simple to use, it is as responsive as the cumulative method and has the additional advantage of a 0 to 100-point scale.

The main limitation of the present study was with regard to the generalizability of the results. Although the Patient-Specific Index was the most responsive type of scale used in this study, patient-specific scales need to be studied in other populations of patients who have osteoarthrosis of the hip, including those managed at different institutions and by different surgeons and those who have different educational levels and socioeconomic status, as well as in patients who have conditions other than osteoarthrosis.

In conclusion, combining individual ratings of the importance and severity of complaints to create the Patient-Specific Index was shown to be reliable, valid, and responsive. The version of the Patient-Specific Index that simply sums together patients' ratings of severity and importance was the simplest to use and was the most responsive type of scale for evaluation of the results of total hip arthroplasty.

NOTE: The authors thank Dr. James P. Waddell for allowing them to evaluate his patients.

	Footnotes

 
*No benefits in any form have received or will be received from a commercial party related directly or indirectly to the subject of this article. Funds were received in the total or partial support of the research or clinical study presented in this article. The funding sources were a scholarship from the Medical Research Council of Canada (J. G. W.), a fellowship from the Ontario Ministry of Health (N. L. Y.), and the Arthritis Society of Canada.

Read in part at the Annual Meeting of the Canadian Orthopaedic Research Society, Halifax, Nova Scotia, Canada, June 3, 1995.

The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada. Please address requests for reprints to Dr. Wright. E-mail address:jgwright@resunix.sickkids.on.ca (Dr. Wright).

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Amadio, P. C.: Editorial. Outcomes measurements. More questions; some answers. J. Bone and Joint Surg., 75-A: 1583-1584, Nov. 1993.[Free Full Text]
2. Andersson, G.: Hip assessment: a comparison of nine different methods. J. Bone and Joint Surg., 54-B(4): 621-625, 1972.
3. Bartko, J. J.: The intraclass correlation coefficient as a measure of reliability. Psychol. Rep., 19: 3-11, 1966.[Medline]
4. Bell, M. J.; Bombardier, C.; and Tugwell, P.: Measurement of functional status, quality of life, and utility in rheumatoid arthritis. Arthrit. and Rheumat., 33: 591-601, 1990.
5. Bellamy, N.: Critical review of clinical assessment techniques for rheumatoid arthritis trials: new developments. Scandinavian J. Rheumatol, Supplement 80: 3-16, 1989.
6. Bellamy, N.: Pain assessment in osteoarthritis: experience with the WOMAC osteoarthritis index. Sem. Arthrit. and Rheumat., 18 (Supplement 2): 14-17, 1989.
7. Bellamy, N., and Buchanan, W. W.: A preliminary evaluation of the dimensionality and clinical importance of pain and disability in osteoarthritis of the hip and knee. Clin. Rheumatol., 5: 231-241, 1986.[Medline]
8. Bellamy, N.; Buchanan, W. W.; Goldsmith, C. H.; Campbell, J.; and Duku, E.: Signal measurement strategies: are they feasible and do they offer any advantage in outcome measurement in osteoarthritis?. Arthrit. and Rheumat., 33: 739-745, 1990.
9. Bellamy, N.; Buchanan, W. W.; Goldsmith, C. H.; Campbell, J.; and Stitt, L. W.: Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J. Rheumatol., 15: 1833-1840, 1988.[Medline]
10. Bombardier, C.; Ware, J.; Russell, I. J.; Larson, M.; Chalmers, A.; and Read, J. L.: Auranofin therapy and quality of life in patients with rheumatoid arthritis. Results of a multicenter trial. Am. J. Med., 81: 565-578, 1986.[Medline]
11. Bombardier, C.; Melfi, C. A.; Paul, J.; Green, R.; Hawker, G.; Wright, J.; and Coyte, P.: Comparison of a generic and a disease-specific measure of pain and physical function after knee replacement surgery. Med. Care, 33 (Supplement 4): 131-AS144, 1995.
12. Callaghan, J. J.; Dysart, S. H.; Savory, C. F.; and Hopkinson, W. J.: Assessing the results of hip replacement. A comparison of five different rating systems. J. Bone and Joint Surg., 72-B(6): 1008-1009, 1990.
13. Charnley, J.: The long-term results of low-friction arthroplasty of the hip performed as a primary intervention. J. Bone and Joint Surg., 54-B(1): 61-76, 1972.
14. Dawson, J.; Fitzpatrick, R.; Carr, A.; and Murray, D.: Questionnaire on the perceptions of patients about total hip replacement. J. Bone and Joint Surg., 78-B(2): 185-190, 1996.[Abstract/Free Full Text]
15. Deyo, R. A.: Measuring functional outcomes in therapeutic trials for chronic disease. Control. Clin. Trials, 5: 223-240, 1984.[Medline]
16. Deyo, R. A., and Centor, R. M.: Assessing the responsiveness of functional scales to clinical change: an analogy to diagnostic test performance. J. Chronic Dis., 39: 897-906, 1986.[Medline]
17. Deyo, R. A., and Inui, T. S.: Toward clinical applications of health status measures: sensitivity of scales to clinically important changes. Health Serv. Res., 19: 277-289, 1984.
18. Donner, A.: Approaches to sample size estimation in the design of clinical trials—a review. Statist. Med., 3: 199-214, 1984.
19. Donner, A., and Eliasziw, M.: Sample size requirements for reliability studies. Statist. Med., 6: 441-448, 1987.
20. Ellwood, P. M.: Shattuck lecture—outcomes management. A technology of patient experience. New England J. Med., 318: 1549-1556, 1988.[Medline]
21. Feinstein, A. R.: Clinimetrics. New Haven, Yale University Press, 1987.
22. Fleiss, J. L.: The Design and Analysis of Clinical Experiments. New York, Wiley, 1986.
23. Foppa, I.; Noack, H.; and Minder, C. E.: The relation of reported symptoms to social, individual, and behavioral indicators of ill-health: is the number of reported symptoms a unique general dimension of ill-health?. J. Clin. Epidemiol., 48: 941-948, 1995.[Medline]
24. Galante, J.: Editorial. The need for a standardized system for evaluating results of total hip surgery. J. Bone and Joint Surg., 67-A: 511-512, April 1985.[Free Full Text]
25. Galante, J.: Editorial. Evaluation of results of total hip replacement. J. Bone and Joint Surg., 72-A: 159-160, Feb. 1990.[Free Full Text]
26. Gartland, J. J.: Orthopaedic clinical research. Deficiencies in experimental design and determinations of outcome. J. Bone and Joint Surg., 70-A: 1357-1364, Oct. 1988.[Abstract/Free Full Text]
27. Gross, M.: A critique of the methodologies used in clinical studies of hip-joint arthroplasty published in the English-language orthopaedic literature. J. Bone and Joint Surg., 70-A: 1364-1371, Oct. 1988.[Abstract/Free Full Text]
28. Guyatt, G.; Walter, S.; and Norman, G.: Measuring change over time: assessing the usefulness of evaluative instruments. J. Chronic Dis., 40: 171-178, 1987.[Medline]
29. Guyatt, G. H.; Berman, L. B.; Townsend, M.; and Taylor, D. W.: Should study subjects see their previous responses?. J. Chronic Dis., 38: 1003-1007, 1985.[Medline]
30. Guyatt, G. H.; Townsend, M.; Berman, L. B.; and Keller, J. L.: A comparison of Likert and visual analogue scales for measuring change in function. J. Chronic Dis., 40: 1129-1133, 1987.[Medline]
31. Guyatt, G. H.; Deyo, R. A.; Charlson, M.; Levine, M. N.; and Mitchell, A.: Responsiveness and validity in health status measurement: a clarification. J. Clin. Epidemiol., 42: 403-408, 1989.[Medline]
32. Harris, W. H.: Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J. Bone and Joint Surg., 51-A: 737-755, June 1969.[Abstract/Free Full Text]
33. Harris, W. H., and Sledge, C. B.: Total hip and total knee replacement. New England J. Med., 323: 801-807, 1990.[Medline]
34. Johanson, N. A.; Charlson, M. E.; Szatrowski, T. P.; and Ranawat, C. S.: A self-administered hip-rating questionnaire for the assessment of outcome after total hip replacement. J. Bone and Joint Surg., 74-A: 587-597, April 1992.[Abstract/Free Full Text]
35. Johnston, R. C.; Fitzgerald, R. H., Jr.; Harris, W. H.; Poss, R.; Müller, M. E.; and Sledge, C. B.: Clinical and radiographic evaluation of total hip replacement. A standard system of terminology for reporting results. J. Bone and Joint Surg., 72-A: 161-168, Feb. 1990.[Free Full Text]
36. Kantz, M. E.; Harris, W. J.; Levitsky, K.; Ware, J. E., Jr.; and Davies, A. R.: Methods for assessing condition-specific and generic functional status outcomes after total knee replacement. Med. Care, 30 (Supplement 5): 240-MS252, 1992.
37. Katz, J. N.; Larson, M. G.; Phillips, C. B.; Fossel, A. H.; and Liang, M. H.: Comparative measurement sensitivity of short and longer health status instruments. Med. Care, 30: 917-925, 1992.[Medline]
38. Katz, J. N.; Phillips, C. B.; Poss, R.; Harrast, J. J.; Fossel, A. H.; Liang, M. H.; and Sledge, C. B.: The validity and reliability of a total hip arthroplasty outcome evaluation questionnaire. J. Bone and Joint Surg., 77-A: 1528-1534, Oct. 1995.[Abstract/Free Full Text]
39. Kavanagh, B. F., and Fitzgerald, R. H., Jr.: Clinical and roentgenographic assessment of total hip arthroplasty. A new score. Clin. Orthop., 193: 133-140, 1985.
40. Kazis, L. E.; Anderson, J. J.; and Meenan, R. F.: Effect sizes for interpreting changes in health status. Med. Care, 27 (Supplement 3): 178-S189, 1989.
41. Lachin, J. M.: Introduction to sample size determination and power analysis for clinical trials. Control. Clin. Trial, 2: 93-113, 1981.[Medline]
42. Larson, C. B.: Rating scale for hip disabilities. Clin. Orthop., 31: 85-93, 1963.[Medline]
43. Laupacis, A.; Bourne, R.; Rorabeck, C.; Feeny, D.; Wong, C.; Tugwell, P.; Leslie, K.; and Bullas, R.: The effect of elective total hip replacement on health-related quality of life. J. Bone and Joint Surg., 75-A: 1619-1626, Nov. 1993.[Abstract/Free Full Text]
44. Liang, M. H., and Jette, A. M.: Measuring functional ability in chronic arthritis. Arthrit. and Rheumat., 24: 80-86, 1981.
45. Liang, M. H.; Larson, M. G.; Cullen, K. E.; and Schwartz, J. A.: Comparative measurement efficiency and sensitivity of five health status instruments for arthritis research. Arthrit. and Rheumat., 28: 542-547, 1985.
46. Liang, M. H.; Katz, J. N.; Phillips, C.; Sledge, C.; Cats-Baril, W.; and The American Academy of Orthopaedic Surgeons Task Force on Outcome Studies: The Total Hip Arthroplasty Outcome Evaluation Form of The American Academy of Orthopaedic Surgeons. Results of a nominal group process. J. Bone and Joint Surg., 73-A: 639-646, June 1991.[Free Full Text]
47. Liang, M. H.; Cullen, K. E.; Larson, M. G.; Thompson, M. S.; Schwartz, J. A.; Fossel, A. H.; Roberts, W. N.; and Sledge, C. B.: Cost-effectiveness of total joint arthroplasty in osteoarthritis. Arthrit. and Rheumat., 29: 937-943, 1986.
48. Lieberman, J. R.; Dorey, F.; Shekelle, P.; Schumacher, L.; Thomas, B. J.; Kilgis, D. J.; and Finerman, G. A. M.: Differences in patient versus physician evaluation after total hip arthroplasty. Orthop. Trans., 19: 307, 1995.
49. McHorney, C. A.; Ware, J. E., Jr.; Rogers, W.; Raczek, A. E.; and Lu, J. F.: The validity and relative precision of MOS short- and long-form health status scales and Dartmouth COOP charts. Results from the Medical Outcomes Study. Med. Care, 30 (Supplement 5): 253-MS265, 1992.
50. MacKenzie, C. R.; Charlson, M. E.; DiGioia, D.; and Kelley, K.: Can the Sickness Impact Profile measure change? An example of scale assessment. J. Chronic Dis., 39: 429-438, 1986.[Medline]
51. MacKenzie, C. R.; Charlson, M. E.; DiGioia, D.; and Kelley, K.: A patient-specific measure of change in maximal function. Arch. Intern. Med., 146: 1325-1329, 1986.[Abstract/Free Full Text]
52. Merle d'Aubigné, R., and Postel, M.: Functional results of hip arthroplasty with acrylic prosthesis. J. Bone and Joint Surg., 36-A: 451-475, June 1954.[Abstract/Free Full Text]
53. National Institutes of Health Consensus Conference: Total hip replacement. Consensus Development Panel on Total Hip Replacement. J. Am. Med. Assn., 273: 1950-1956, 1995.[Abstract/Free Full Text]
54. Nunnally, J. C.: Psychometric Theory. Ed. 2. New York, McGraw-Hill, 1978.
55. O'Boyle, C. A.; McGee, H.; Hickey, A.; O'Malley, K.; and Joyce, C. R.: Individual quality of life in patients undergoing hip replacement. Lancet, 339: 1088-1091, 1992.[Medline]
56. Patrick, D. L., and Deyo, R. A.: Generic and disease-specific measures in assessing health status and quality of life. Med. Care, 27 (Supplement 3): 217-S232, 1989.
57. Rosner, B.: Fundamentals of Biostatistics. Ed. 4, p. 675. Belmont, California, Duxbury Press, 1995.
58. Salvati, E. A., and Wilson, P. D., Jr.: Long-term results of femoral-head replacement. J. Bone and Joint Surg., 55-A: 516-524, April 1973.[Abstract/Free Full Text]
59. Shrout, P. E., and Fleiss, J. L.: Intraclass correlations: uses in assessing rater reliability. Psychol. Bull., 86: 420-428, 1979.[Medline]
60. Stewart, A. L.; Hays, R. D.; and Ware, J. E., Jr.: The MOS short-form general health survey. Reliability and validity in a patient population. Med. Care, 26: 724-735, 1988.[Medline]
61. Tugwell, P.; Bombardier, C.; Buchanan, W. W.; Goldsmith, C. H.; Grace, E.; and Hanna, B.: The MACTAR Patient Preference Disability Questionnaire—an individualized functional priority approach for assessing improvement in physical disability in clinical trials in rheumatoid arthritis. J. Rheumatol., 14: 446-451, 1987.[Medline]
62. Tugwell, P.; Bombardier, C.; Bell, M.; Bennett, K.; Bensen, W.; Grace, E.; Hart, L.; and Goldsmith, C.: Current quality-of-life research challenges in arthritis relevant to the issue of clinical significance. Control. Clin. Trials, 12 (Supplement 4): 217S-225S, 1991.
63. Tugwell, P.; Bombardier, C.; Buchanan, W. W.; Goldsmith, C.; Grace, E.; Bennett, K. J.; Williams, H. J.; Egger, M.; Alarcon, G. S.; Guttadauria, M.; Yarbora, C.; Polisson, R. P.; Szydlo, L.; Luggen, M. E.; Billingsley, L. M.; Ward, J. R.; and Marks, C.: Methotrexate in rheumatoid arthritis. Impact on quality of life assessed by traditional standard-item and individualized patient preference health status questionnaires. Arch. Intern. Med., 150: 59-62, 1990.[Abstract/Free Full Text]
64. Ware, J. E., Jr., and Sherbourne, C. D.: The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med. Care, 30: 473-483, 1992.[Medline]
65. Wells, G. A.; Tugwell, P.; Kraag, G. R.; Baker, P. R.; Groh, J.; and Redelmeier, D. A.: Minimum important difference between patients with rheumatoid arthritis: the patient's perspective. J. Rheumatol., 20: 557-560, 1993.[Medline]
66. Wennberg, J. E.: Outcomes research, cost containment, and the fear of health care rationing. New England J. Med., 323: 1202-1204, 1990.[Medline]
67. Wiklund, I., and Romanus, B.: A comparison of quality of life before and after arthroplasty in patients who had arthrosis of the hip joint. J. Bone and Joint Surg., 73-A: 765-769, June 1991.[Abstract/Free Full Text]
68. Wright, J. G., and Feinstein, A. R.: Improving the reliability of orthopaedic measurements. J. Bone and Joint Surg., 74-B(2): 287-291, 1992.
69. Wright, J. G.; Rudicel, S.; and Feinstein, A. R.: Ask patients what they want. Evaluation of individual complaints before total hip replacement. J. Bone and Joint Surg., 76-B(2): 229-234, 1994.

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