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- PATIENTS AND METHODS
- APPENDIX A
Destruction of the elbow joint occurs most commonly in connection with rheumatoid arthritis (RA) and, occasionally, following intraarticular fracture. It can greatly affect an individual's health and quality of life (QOL). Worldwide, RA has a lifetime prevalence of 1–2%, and the elbow joint is affected in 20–50% of these cases (1). Of all elbow prostheses, 80% are implanted due to RA (2, 3). Loss of elbow motion is considered more disabling than loss of shoulder or wrist function, since normal elbow function is required for positioning the hand in space, which is crucial in the performance of activities of daily living (ADL), e.g., reaching the hand to the mouth (1).
In the treatment of primary or secondary elbow joint destruction, the development of artificial joint replacement has become the most important therapy option in the prevention of permanent disability (1, 4, 5). Especially in RA, total elbow arthroplasty has become a well-accepted and safe procedure. With the introduction of the semiconstrained principle, the complication rates reduced from 45% in the late 1970s to 11–20% in the 1990s (1, 3, 5, 6). There are multiple reports in the literature of the mid- and long-term results after elbow arthroplasty. However, most of these are based on examiner-dependent outcome measures; only few studies have employed standardized, valid, and comprehensive assessment instruments (7–11). Furthermore, no studies have examined the comparability of the various instruments used, in relation to their relative validity, clinical utility, or specificity. This is also true in relation to other elbow conditions.
The importance of valid clinical outcome and QOL assessments has been discussed in the authors' previous cross-sectional study of patients after shoulder arthroplasty (12). Analogous to that study, and with the goal of developing a standardized assessment tool that would be feasible for use in the clinical environment, we tested a set of both clinical (physician-assessed) and patient self-administered health measurement instruments in a cross-sectional followup examination of patients 6–19 years after total elbow arthoplasty. The first aim of the study was to describe the health status and QOL of these patients compared with population-based normative data, using a holistic, comprehensive, quantitative assessment approach. The second aim was to assess the validity of the assessment tools, the quality of the data obtained, and the feasibility of the instruments' use in the daily clinical routine to arrive at recommendations for an optimal set of instruments. It was hoped that the examination of a broad spectrum of parameters would contribute to the development of a standardized assessment tool for use in the clinical environment with broad use in different patient settings.
- Top of page
- PATIENTS AND METHODS
- APPENDIX A
Perfect health, reflected by a score of 100, cannot be realistically expected for a 64-year-old person with RA (75% of our patients had RA) and with a high prevalence of comorbid conditions (71% of the patients had ≥1 comorbid condition) 6–19 years after total elbow arthroplasty. This is discussed in detail in our previous study, with respect to total shoulder arthroplasty patients (12).
As observed in the shoulder patients, some functional limitation was also present in the elbow patients, evidenced by the low scores on the function scales and subscales (see Table 2 and Figure 1). However, this did not substantially affect overall health perception and QOL: the elbow patients rated their general health perception (SF-36) and mental health (5 dimensions of the SF-36) as high, and within the range of normal population values. To adequately perform ADL, certain functional abilities are required. Elbow flexion was 120° or more in 92 of the 96 (96%) arthroplasty joints, a necessary condition to reach the mouth using the hand. The elbow patients were highly satisfied with the result of their arthroplasty (mean pmASES satisfaction score 81.0; 92% with VAS score between 6 and 10 where 0 = worst and 10 = best), and 87% would choose the operation again if necessary. Because pain is the most important factor affecting health perception and QOL (31), this result is not surprising; the patients in the present study reported low pain levels in the pmASES, the PREE, the DASH symptoms score (in which 50% items enquire about pain) (75% of the norm), and the SF-36 (108% of the norm). The apparent discrepancy that 18% of the patients felt unchanged or worse postoperatively, but only 13% would not do the operation again, most likely reflects a certain proportion of the patients who expected to worsen had they not undergone arthroplasty. Patients with bilateral total elbow arthroplasty had poorer health than those with unilateral. Thus, the relative proportion of bilateral and unilateral arthroplasties in any given cohort is important to know because it can confound the overall result for the given patient sample.
Compared with our shoulder arthroplasty patients (mean age 65.1 years, 77% women, 77% with ≥1 comorbidity, 49% with RA) (12), the elbow arthroplasty patients (mean age 64.1 years, 71% women, 71% ≥1 comorbidity, 75% with RA) were more functionally impaired. They displayed lower scores for SF-36 physical functioning (elbow: 48.7 versus shoulder: 54.9), DASH (55.3 versus 64.0), SF-36 role emotional (74.8 versus 80.5), and slightly less in the SF-36 vitality (48.4 versus 52.9). The elbow patients showed better health in the SF-36 bodily pain (elbow: 59.1 versus shoulder: 55.4) and in the SF-36 general health (65.0 versus 53.1), such that overall, the physical and mental summary scores were not different between the 2 groups.
In relation to range of motion and patient satisfaction, the results for our elbow arthroplasty patients were comparable with those reported in other studies (10, 32, 33). In a cross-sectional 50-month followup study of 18 RA patients (21 joints with Coonrad-Morrey endoprostheses), Hildebrand et al showed a mean DASH score of 53 (our patients 55.3), an SF-36 PCS of 27 (ours 37.2), and an SF-36 MCS of 56 (ours 52.3) (10). In the same study, a group of patients with posttraumatic destruction of the elbow (18 patients and elbows) showed SF-36 PCS and the DASH scores that were about 20% higher than those of the RA patients. Consistent with these findings, Garcia et al reported a high mean DASH score of 77 in 16 posttraumatic patients, 3–5.5 years after Coonrad-Morrey arthroplasty; 15 of the 16 patients were satisfied with the result (33).
The patient's questionnaire set (containing the sociodemographic questionnaire, the self-reporting questionnaire, the SF-36, the DASH, the PREE, and the pmASES) needed on average no more than 30 minutes to complete. The evaluation of the clinical parameters was part of the physical examination, which lasted 10–15 minutes, including 3 minutes to complete the clinical part of the cmASES.
Normal distribution and low floor and ceiling effects are positive properties of a scale, as discussed in detail in our previous article (12): Normally distributed scores allow to use sensitive parametric significance tests. Low floor and ceiling effects allow to differentiate between the patients by the score. In contrast, 2 patients with a score of 100 cannot be differentiated by this score, although their outcome may be different. According to these measurement properties, the SF-36 physical functioning, general health, mental health, and both summary scores; all DASH subscores; the PREE pain and function scores; the pmASES function and total score; and the cmASES motion and total scores were able to reflect best the outcome of the present patient sample.
Surprisingly, and in contrast to the shoulder arthroplasty study (12), in factor analysis the DASH (total score) loaded on the same factor (Table 4) and correlated (Table 3) slightly better (r = 0.76) with the generic SF-36 PCS than with the elbow-specific PREE (r = 0.68) and pmASES (r = 0.73). Because the DASH is considered to be condition specific, a higher correlation with the other condition-specific instruments than with the generic SF-36 would have been expected. The 24 function items of the DASH thus seemed not to be particularly sensitive to elbow-specific disabilities. However, the DASH symptom items may be more sensitive to elbow problems than the SF-36, as the DASH score was far lower in relation to the normative value than was the SF-36 (e.g., bodily pain). According to this analysis, all the information yielded by the DASH is covered by the SF-36 and the condition-specific PREE or pmASES. The SF-36 is unique in capturing mental health and psychosocial dimensions. Also in contrast to the shoulder study findings, the clinical assessment (cmASES) was highly correlated with the condition-specific self rating of the pmASES and the PREE. The physician thus seems to assess elbow-specific (but not shoulder-specific) function and symptoms in a similar manner to the patient. However, it is well known that clinical measures of elbow function do not necessarily reflect patient wellbeing, performance levels in ADL and QOL, and vice versa (see reference 29). Thus, clinical and self-rating assessments should both be used simultaneously.
To shorten the set to be used in future clinical practice, just one of either the PREE or the pmASES is recommended for inclusion, since the correlation (r = 0.92) and factor analysis indicated similar and valid constructs for these instruments. This is supported by a construct validity study of the English versions of the PREE and pmASES: the PREE had a Pearson's correlation coefficient of 0.93–0.96 with pmASES pain and 0.61–0.73 with pmASES function (23).
The ability to discriminate between 2 different conditions of expected differing severity (in this case, posttraumatic versus RA) is another positive property of an instrument. An instrument that does this well helps to characterize 2 different diseases by the levels of the scores. In the logistic regression analysis, the SF-36 PCS and the DASH were the best instruments for discriminating between the 2 conditions examined. Overall, the set containing all instruments showed high sensitivity and specificity in the prediction of RA and posttraumatic condition, as shown by the considerably high area under the receiver operating characteristic curve of 0.86 (an area of 1.00 would reveal perfect discrimination with 100% sensitivity and 100% specificity) (34).
It is important to correct the normative values of an instrument for the presence and absence of comorbid conditions, as well as for sex and age (12), if they are to be used for comparative purposes in clinical studies. In the present study, this was possible for both the SF-36 and the DASH, but not for the other instruments.
The strengths of the present study include the comprehensive nature of the assessment (which covered general health and QOL, subjective patient self ratings, and objective clinical findings) and the use of normative data corrected for age, sex, and comorbidity in interpreting the patients' scores. The limitations included the study's cross-sectional uncontrolled design, the inherent problems of self assessment (requiring a certain level of psychointellectual ability and compliance) and the low response rate (79 of 192 possible patients, 41%) due to the relatively long followup time leading to a high rate of deaths (37%). Furthermore, the health status of the nonresponders may have been worse than that of the patients who took part, leading to an overestimation of the outcome. However, this is an inherent problem of any such retrospective study (participation bias, a form of selection bias).
The outcome data are presently only applicable to severely affected RA and posttraumatic patients needing arthroplasty. However, the instruments' psychometric properties can be expected to be consistent in different patient settings, as almost all score levels were represented by the patients examined. Therefore, we expect that the set can be successfully used in other clinical settings, e.g., primary care, although this would of course require further verification.
Using an extensive, comprehensive set of instruments, it was shown in patients who had undergone total elbow arthroplasty 6–19 years ago, general wellbeing, QOL, and satisfaction with treatment were good on average. Some specific functions remained significantly impaired, but appeared not to play a decisive role in the performance of tasks of daily living and perception of QOL in general. This is important, because it suggests that a study relying only on functional measures would overlook the high self-perceived QOL and satisfaction of the patients, which may be decisive in determining future utilization of health care resources.
According to the present cross-sectional analysis, an instrument set consisting of the SF-36 combined with the patient and clinical mASES (or the PREE, if it must be short), together with sociodemographic and comorbidity assessments, is proposed for future clinical use. The DASH is not necessary because it is no more specific than the SF-36 and can be replaced by the PREE or the patient mASES, which has the added advantage of assessing the left and the right limbs separately. However, before the instrument set can be implemented in clinical practice, the responsiveness of the various questionnaires should be examined. This will require a longitudinal study to examine the sensitivity to change of the instruments after specific interventions. In accordance with the World Health Organizations' International Classification of Functioning, Disability and Health concept, the final set of instruments should allow a valid, sensitive, patient-orientated, and clinically relevant assessment, within the normal clinical routine (31, 35). It should provide the opportunity to compare results among different conditions, diseases, and interventions, and with those of the general population.