Validation of single‐factor structure and scoring protocol for the health assessment questionnaire‐disability index

Objective

The extensively used Health Assessment Questionnaire Disability Index (HAQ‐DI) has been well received by the research and clinical community, notably because of its measurement strengths including reliability and stability of scores over time, utility in observational studies and clinical trials, predictive relationship with morbidity and mortality in rheumatoid arthritis (RA), and its translation for use in different countries. However, HAQ‐DI scoring has not been validated. The purpose of this study was to examine the structural validity of the HAQ‐DI and evaluate the latent factors underlying HAQ‐DI scoring.

Methods

This study used a cross‐validation approach on a total of 278 patients with RA. Exploratory and confirmatory factor analyses were performed.

Results

Results yielded a single‐factor HAQ‐DI score, which favored the current scoring system of the HAQ‐DI. Additionally, modification indices suggested improved model fit with the secondary inclusion of correlated residual scores from a motor skills subdomain.

Conclusion

The current study provides the first validation of the HAQ‐DI scoring system as determined by its latent factor structure. In addition, the findings suggest some benefit from a secondary interpretation of the scores based on domains that measure motor skills.

     

Validity of self‐administered quality of well‐being scale in musculoskeletal disease

Objective

To evaluate the self‐administered Quality of Well‐Being (QWB‐SA) Scale for patients with rheumatic diseases.

Methods

Family medicine patients (n = 562) and rheumatology patients (n = 334) were assessed using the following tools: QWB‐SA, Health Assessment Questionnaire (HAQ), Arthritis Impact Measurement Scales (AIMS), and Rapid Assessment of Disease Activity in Rheumatology (RADAR).

Results

Patients with arthritis had significantly lower QWB‐SA scores and significantly higher HAQ scores than family medicine patients with and without adjustment for covariates. The QWB‐SA was significantly associated with quartiles from the RADAR, AIMS, and HAQ, providing evidence for the validity of the generic measure in patients with arthritis. Discriminant function analysis was used to create an arthritis‐specific scoring system for the QWB‐SA. Analyses demonstrated systematic relationships between the Quality of Well‐Being arthritis composite and the disease‐specific RADAR, AIMS, and HAQ.

Conclusions

Evidence supports the validity of the QWB‐SA for patients with rheumatic diseases. QWB‐SA items can be used to calculate an arthritis‐specific score. The QWB‐SA can be used to gain generic information for cost‐utility analysis and disease‐specific outcomes information for patients with arthritis.

     

Validation of a rheumatoid arthritis health‐related quality of life instrument,the CSHQ‐RA

Objective

To test the validity and reliability of a newly developed disease‐specific multidimensional quality of life instrument: the Cedars‐Sinai Health‐Related Quality of Life Instrument (CSHQ‐RA).

Methods

A total of 350 rheumatoid arthritis (RA) patients were asked to complete the CSHQ‐RA at 2 time points (4 weeks apart). Patients also completed the Medical Outcomes Study Short Form 36 (SF‐36) and the Stanford Health Assessment Questionnaire (HAQ) Disability Index (DI) at the second time point. Construct validity was tested, using Pearson's correlations, by comparing subscale scores on the CSHQ‐RA to those obtained from the mental component summary (MCS) and physical component summary (PCS) of the SF‐36. HAQ DI scores were used to assess the discriminant validity of the CSHQ‐RA. Intraclass correlation coefficients (ICCs) were used to assess test–retest reliability.

Results

Response rates for the first and second survey were 83% (291) and 93% (276), respectively; 84% of respondents were women, and mean age was 57 years. Mean scores ± SDs on instruments were: HAQ 0.73 ± 0.69; MCS 49 ± 12; and PCS 33 ± 11. Pearson's correlations between the CSHQ‐RA subscale scores and the SF‐36 scores ranged from 0.55 to 0.76 (P < 0.001). Analysis of variance indicate that scores on the CSHQ‐RA discriminated between levels of physical disability as measured by the HAQ (P < 0.001). Test–retest reliability was demonstrated in the instrument's subscale scores (ICC 0.70–0.90).

Conclusion

These results support the construct validity, discriminant validity, and reliability of the CSHQ‐RA as a measure that captures the impact of RA on patients' health‐related quality of life.

     

Validation of a manual ability questionnaire in patients with systemic sclerosis

Objective

To adapt and validate a manual ability questionnaire, the ABILHAND, developed through the Rasch methodology in patients with systemic sclerosis (SSc).

Methods

The original version of the ABILHAND, which includes 81 manual daily activities, was presented to 156 patients with SSc. They were asked to provide their perceived difficulty in performing each manual activity on a 3‐level scale: impossible, difficult, or easy. Items were selected from well‐established psychometric criteria. The patients were reassessed 1 month later to test the reproducibility. Concomitantly, they were clinically evaluated for their disease activity/severity, and their functional ability was tested with the Health Assessment Questionnaire (HAQ).

Results

The 26 selected items defined a unidimensional and linear measure of manual ability and showed a continuous progression in their difficulty. The item difficulty hierarchy was invariant across 12 patient‐related factors and the manual ability score was reproducible over time. Finally, the manual ability was significantly poorer in SSc patients with more severe disease, and was negatively correlated with the HAQ score (ρ = ?0.733).

Conclusion

The SSc‐adapted ABILHAND questionnaire is a reliable, valid, reproducible, linear, and unidimensional measure to assess and followup on the manual ability of patients with SSc; therefore, it could become a useful additional tool in clinical trials to assess treatment efficacy.

     

Development and validation of the revised Cedars‐Sinai health‐related quality of life for rheumatoid arthritis instrument

Objective

To improve accuracy and content coverage of the original 33‐item Cedars‐Sinai Health‐Related Quality of Life for Rheumatoid Arthritis Instrument (CSHQ‐RA).

Methods

A total of 312 RA patients from 55 sites were screened in a 24‐week trial. Patients completed an expanded 48‐item version of the CSHQ‐RA, Medical Outcomes Study Short Form 36 (MOS SF‐36), and Stanford Health Assessment Questionnaire (HAQ) Disability Index at 5 visits. The revised CSHQ‐RA was created based on response frequencies and distributions, item‐to‐item correlation, factor and Rasch analysis, and input from experts. Psychometric evaluation included internal consistency, test–retest reliability, convergent and discriminant validity, and responsiveness. Minimum clinically important difference (MCID) was also measured.

Results

Response rates were 93% at baseline and 71% at 12 weeks. Eighty‐one percent of respondents at baseline were women, mean ± SD age was 52 ± 12 years, and mean ± SD duration of RA was 10.8 ± 10.4 years. The revised CSHQ‐RA included 36 items measuring 7 domains (4 original and 3 new). All Cronbach's alpha coefficients were >0.8, indicating good internal consistency. Test–retest reliability measured intraclass correlation coefficients, which ranged from 0.86 to 0.95. All 7 domains correlated significantly with the MOS SF‐36 and HAQ, indicating good convergent validity. Analysis of variance of disability group scores showed good discriminant validity (P < 0.0001). The MCIDs ranged from 6.2 for social well‐being to 14.8 for pain/discomfort.

Conclusion

The revised CSHQ‐RA was validated using a broader RA patient population. It captures 3 additional domains (social well‐being, pain/discomfort, and fatigue), which allow for measuring all important aspects of health‐related quality of life.

     

Development and preliminary validation of a Children's Arthritis Self‐Efficacy Scale

Objective

To develop a valid and reliable measure of arthritis self‐efficacy for use with school‐age children with juvenile idiopathic arthritis (JIA).

Methods

Construction of the 11‐item Children's Arthritis Self‐Efficacy Scale (CASE) was based on an existing body of knowledge and the results of focus groups with children, their parents, and health professionals. Data for validation of the CASE were collected by self‐administered questionnaires completed by 89 children and 151 caregivers.

Results

Analyses revealed a 3‐factor structure relating to self‐efficacy for managing symptoms, emotional consequences, and activities, explaining 76.5% of the total variance. The CASE demonstrated high internal consistency, concurrent validity, and construct validity.

Conclusion

Preliminary findings suggest that the CASE is worthy of further psychometric testing and may have the potential to help delineate variations in adjustment among children with JIA.

     

A longitudinal study of the effect of disease activity and clinical damage on physical function over the course of psoriatic arthritis: Does the effect change over time?

Objective

To investigate whether there are differential effects of disease activity and damage on physical functioning as measured by the Health Assessment Questionnaire (HAQ) over the course of psoriatic arthritis (PsA).

Methods

Between June 1993 and March 2005, 382 patients attending the University of Toronto PsA clinic had completed ≥2 HAQs on an annual basis. At the time of each HAQ assessment, clinical and laboratory measures of disease activity and damage were recorded. Generalized linear mixed‐effects models were used to investigate the longitudinal relationship between disease activity, damage, and the HAQ score. To avoid floor effects that would arise in a single mixed‐effects model, we adopted a 2‐part model.

Results

The number of actively inflamed joints (measure of disease activity) and the number of clinically deformed joints (measure of damage) were positively and significantly related to the HAQ score. Furthermore, interaction terms for illness duration with the number of actively inflamed joints were statistically significant, with or without inclusion of the erythrocyte sedimentation rate and morning stiffness in the model (P = 0.029 and P < 0.001, respectively). The positive effects of actively inflamed joints on the level of the HAQ score decreased over increasing duration of PsA. There was less evidence to suggest that the positive effect of joint damage on the HAQ score increased over time.

Conclusion

Our results support the view that the influence of disease activity on HAQ scores declines with increased disease duration. We could not demonstrate strong evidence that the effect of clinical damage increases over the course of illness.

     

Influence of age and sex on functional outcome over time in a cohort of patients with recent-onset inflammatory polyarthritis: results from the Norfolk Arthritis Register

Objective

It has been found that women with rheumatoid arthritis (RA) have a poorer prognosis than men. However, the impact of age at symptom onset is unclear. We investigated the relationship between these factors and functional disability in patients with recent‐onset inflammatory polyarthritis (IP).

Methods

A total of 3,666 patients (66% women) were registered with the Norfolk Arthritis Register between 1990 and 2008. Functional disability was assessed using the Health Assessment Questionnaire (HAQ), adjusted for age at HAQ completion. Linear random‐effects models were used to examine HAQ score over time, by sex and age at symptom onset (early = age <55 years, late = age 55–74 years, very late = age ≥75 years).

Results

Women had higher HAQ scores over time than men (mean difference 0.29; 95% confidence interval [95% CI] 0.25, 0.34). Men with late‐onset IP had lower baseline HAQ scores than men with early onset (mean difference ?0.14; 95% CI ?0.29, ?0.001). Women had comparable baseline HAQ scores at all ages of onset. Both sexes showed the greatest rate of disability progression in patients with very late onset. Those with early onset had a steady level of disability over time. Adjustment for treatment received, comorbidities, and RA subgroup analysis produced results that were largely similar to the initial analysis.

Conclusion

Female patients have higher HAQ scores than male patients; patients with early symptom onset show the smallest sex difference. Older age at symptom onset is associated with an increasingly steep trajectory of disability progression. The impact of sex on outcome is evident at baseline, whereas the impact of age at symptom onset becomes apparent during long‐term followup.

     

Treatment and nontreatment predictors of health assessment questionnaire disability progression in rheumatoid arthritis: a longitudinal study of 18,485 patients

Objective

To examine predictors of progression of disability in rheumatoid arthritis (RA), as measured by the Health Assessment Questionnaire disability index (HAQ), and to determine rates of progression during biologic treatment.

Methods

We followed 18,485 RA patients for up to 11 years (mean 3.7 years) in a longitudinal study of RA outcomes. Patients were characterized as having moderate or severe RA versus less severe RA at study entry. Annualized progression rates were determined in multivariable analyses using generalized estimating equations.

Results

Although all of the demographic and severity characteristics were associated with baseline differences in HAQ score, progression was only associated with age, comorbidity, initial severity, and treatment. HAQ score increased fastest in patients ages >65 years (0.031; 95% confidence interval [95% CI] 0.028, 0.034). HAQ progression was independently associated with the presence of baseline cardiovascular disease, hypertension, diabetes mellitus, and the number of comorbid conditions. Annualized progression rates were greater in patients with mild to inactive RA (0.021; 95% CI 0.019, 0.023) than in moderate to severe RA (0.003; 95% CI 0.001, 0.006). The overall progression rate during biologic treatment was 0.008 (95% CI 0.005, 0.011); for patients with moderate to severe RA, the rate was 0.001 (95% CI ?0.005, 0.003).

Conclusion

Age and comorbidity are important predictors of the rate of loss of functional status, and have a stronger effect on HAQ progression than does biologic treatment. There is little difference in progression rates among biologics. Patients with more severe RA progress less than those with less severe RA, a possible function of regression to the mean.

     

Association of functional outcome with both personal‐ and area‐level socioeconomic inequalities in patients with inflammatory polyarthritis

Objective

To describe the relationship between baseline area‐ and person‐level social inequalities and functional disability at 3 years in patients with early inflammatory polyarthritis (IP).

Methods

A total of 1,393 patients with new‐onset IP were recruited and allocated an Index of Multiple Deprivation (IMD) 2004 score based on their area of residence, and a social class based on baseline self‐reported occupation. Differences in the Health Assessment Questionnaire (HAQ) score at baseline and 3 years by IMD or social class were tested. The mean 3‐year change in HAQ score was compared by IMD and social class, and interactions between these measures examined.

Results

Patients from more deprived areas had poorer 3‐year HAQ outcome than those from less deprived areas (P = 0.019, adjusted for baseline HAQ score, age, sex, and symptom duration). The mean difference in HAQ change was most notable between the most deprived (IMD4) and least deprived areas (IMD1) (0.22; 95% confidence interval [95% CI] 0.11, 0.34). There was also a significant difference in HAQ score change between patients of the highest (SCI and II) and lowest social class (SCIV and V) (0.11; 95% CI 0.02, 0.20). For the mean (95% CI) 3‐year change in HAQ score, a significant interaction exists between IMD score and social class and their association with HAQ scores (P = 0.001) to modify outcome: IMD1/SC I and II ?0.23 (95% CI ?0.40, ?0.06) versus IMD 4/SC IV and V 0.15 (95% CI ?0.05, 0.34).

Conclusion

Person‐ and area‐level inequalities combine to modify outcome for rheumatoid arthritis. A person's social circumstance and residential environment have independent effects on outcome and are not just alternative measures of the same exposure.

     

A home‐based two‐year strength training period in early rheumatoid arthritis led to good long‐term compliance: A five‐year followup

Objective

To evaluate the impact of a 2‐year home‐based strength‐training program on physical function in patients with early rheumatoid arthritis (RA) after a subsequent 3‐year followup.

Methods

Seventy patients with early RA were randomized to perform either strength training (experimental group [EG]) or range‐of‐motion exercises (control group [CG]). Maximal strength values were recorded by dynamometers. The Modified Disease Activity Score (DAS28), pain, Health Assessment Questionnaire (HAQ), walking speed, and stair‐climbing speed were also measured.

Results

The maximum strength of assessed muscle groups increased by 19–59% in the EG during the training period and remained at the reached level throughout the subsequent 3 years. Muscle strength improved in the CG by 1–31%, but less compared with the EG. During the 2‐year training period, DAS28 decreased by 50% and 45% and pain by 67% and 39% in the EG and CG, respectively. The differences in muscle strength, DAS28, and HAQ were significantly in favor of the EG both at the 2‐year and 5‐year followup assessments.

Conclusions

The improvements achieved during the 2‐year strength‐training period were sustained for 3 years in patients with early RA.

     

Defining incident radiographic hip osteoarthritis for epidemiologic studies in women

Objective

To evaluate definitions of radiographic hip osteoarthritis (RHOA) for use in longitudinal epidemiologic studies of disease incidence in women.

Methods

We studied 5,839 women from the Study of Osteoporotic Fractures who had had serial pelvic radiographs obtained (mean of 8.3 years apart) and who were followed up (mean followup 7.1 years from the time of the second radiograph) for evaluation of clinical outcomes. Definitions of RHOA were assessed for construct validity (association with symptoms and signs at the time of the second radiograph) and predictive validity (association with total hip replacement [THR] and signs and symptoms a mean of 7.1 years later). Odds ratios (ORs) and 95% confidence intervals were calculated to assess the strength of association using logistic regression.

Results

The cumulative incidence of RHOA ranged from 2.2% to 11.7%. All definitions displayed significant construct validity; the most consistent was found for composite definitions that required the concurrent presence of 2 or more individual radiographic features and definitions based on stringent criteria for joint space narrowing. All definitions except minimum joint space ≤2.5 mm displayed consistent predictive validity. Composite definitions had the strongest associations with THR (OR 10.5–18.5) and hip pain (OR 2.6–2.9). The hips identified as having OA by each definition varied, with especially small overlap between findings using definitions based on osteophytes and those using definitions based on joint space narrowing alone.

Conclusion

Most definitions of incident RHOA display good construct and predictive validity. Composite definitions have the best overall performance, and definitions requiring the presence of both osteophytes (in particular, femoral osteophytes) and joint space narrowing would be recommended for most epidemiologic and genetic studies.

     

Task independence,safety, and adequacy among nondisabled and osteoarthritis‐disabled older women

Objective

To examine the constructs of task independence, safety, and adequacy.

Method

Fifty‐seven nondisabled (ND) and 56 osteoarthritis‐disabled (OAK) women were observed performing daily tasks.

Results

Intercorrelations among the constructs of independence and adequacy were uniformly high, while the relationship of safety to these constructs was moderate and more variable, although stronger in the OAK group. Task performance of the OAK group was consistently less adequate and independent than that of the ND group; however, the groups were generally equivalent in safety. For individual tasks, adequacy best differentiated between the groups. In both groups, those who performed independently also performed safely, but fewer independent OAK participants also performed totally adequately.

Conclusion

The majority of older women who perform tasks independently also perform them safely and adequately; for a clinically significant minority, independence is not always synonymous with safe and adequate performance. Patients may be placed at risk if independence is the only construct used to determine disability.

     

Feasibility and construct validity of the parent willingness‐to‐pay technique for children with juvenile idiopathic arthritis

Objective

To assess the feasibility and construct validity of the willingness‐to‐pay (WTP) technique for measuring health care preferences in families of children with juvenile idiopathic arthritis (JIA).

Methods

Parents were asked to estimate the monthly US dollar amount they would be willing to pay to obtain for their child the following hypothetical drugs: ARTHRO, which guarantees complete clinical response; and NO‐STOM‐ACHE, a drug that eliminates gastrointestinal (GI) symptoms. A yes/no question was used with random assignment of the starting bids. Parents who agreed to pay the starting bid were then asked whether they would be willing to pay 200% and then 400% of this initial bid. Socioeconomic data and information on medications, disease activity, patient physical function, wellbeing, and health‐related quality of life (HRQOL) were obtained.

Results

Sixty‐two families of children with JIA were interviewed. GI symptoms were present in 54%, and 53% of the children had joints with active arthritis or limited range of motion. Four parents (7%) were unwilling to pay anything for any of the studied medications. The mean amount (median; mean percentage of available family income) families were willing to pay was $395 ($300; 15%) for ARTHRO and $109 ($80; 4%) for NO‐STOM‐ACHE. Correlation and regression analysis supported that, adjusted for the available family income, the WTP for ARTHRO was associated with disease activity, pain, and the HRQOL of the patients. After correction for the starting bids and the available family income, the WTP for NO‐STOM‐ACHE was associated with the patient's HRQOL, pain, and the amount of GI discomfort.

Conclusion

The WTP technique is feasible and has construct validity for measuring health care preferences for children with JIA. Relatively large WTP estimates support a possible important negative impact of the disease on families of children with JIA.

     

The relationship between self‐report and performance‐related measures: Questioning the content validity of timed tests

Objective

To examine the determinants of the modest correlation between self‐report and performance‐related measures in patients with osteoarthritis of the hip or knee.

Methods

Measures included the Lower Extremity Functional Scale (LEFS), the self paced walk, timed up‐and‐go, and stair test. Each performance measure consisted of 3 domains: time, pain (visual analog scale), and exertion (Borg scale). Activity specificity was assessed by examining correlations between the LEFS with single activity and multiple activity time scores. Domain specificity was examined by comparing correlations between the LEFS and single and multiple domain scores. The impact of measurement error was considered.

Results

Increasing the number of activity time scores had no effect. Forming a composite performance score based on time, pain, and exertion substantially increased the correlation from 0.44 (composite timed score) to 0.59 (pooled domain and activity score) (P = 0.009).

Conclusion

Performance scores based on time alone appear to inadequately represent the breadth of health concepts associated with functional status.

     

PENTA guidelines for the use of antiretroviral therapy in paediatric HIV infection. Pediatric European Network for Treatment of AIDS

Objective

To produce European Guidelines for the use of antiretroviral therapy (ART) in HIV‐infected children.

Design

Systematic literature review using Medline, the major antiretroviral conference reports, and IDSA recommendations on guideline production.

Setting

Pediatric European Network for Treatment of AIDS (PENTA) Steering Committee.

Outcome measure

Guidelines have been produced for the use of antiretroviral therapy in HIV‐infected children in Europe. Recommendations on when to start ART and which ART to start, with dosages and a summary of the relevant literature, have been produced.

Conclusions

These guidelines are aimed at assisting paediatricians in Europe with ART prescribing, and provide a more cautious approach to starting therapy than current paediatric USA guidelines.

     

Dyspnea assessment and pulmonary hypertension in patients with systemic sclerosis: Utility of the University of California,San Diego,Shortness of Breath Questionnaire

Objective

The University of California in San Diego Shortness of Breath Questionnaire (UCSD SOBQ) has been used to assess dyspnea‐related activity limitation in patients with airway and parenchymal lung disease. We sought to assess the construct validity and responsiveness of the UCSD SOBQ in systemic sclerosis (SSc; scleroderma) patients with incident pulmonary hypertension (PH) and those at high risk of developing PH.

Methods

We used data from 179 patients enrolled in the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma Registry with pre‐PH (defined by criteria on pulmonary function tests and/or echocardiogram) or definite PH with mean pulmonary artery pressure ≥25 mm Hg by right‐sided heart catheterization within 6 months of enrollment. For this analysis, we included those subjects with complete data for self‐reported measures at baseline and at 12 months.

Results

At baseline, the UCSD SOBQ had strong correlations in the expected direction with the disability index (DI) of the Health Assessment Questionnaire (HAQ) (r = 0.71, P < 0.0001), dyspnea assessment by visual analog scale (r = 0.71, P < 0.0001), and the Short Form 36 (SF‐36) health survey physical component summary (PCS) score (r = ?0.77, P < 0.0001), as well as a moderate correlation with the 6‐minute walk test distance (r = ?0.33, P < 0.0001), Borg dyspnea score (r = 0.47, P < 0.0001), and diffusing capacity of carbon monoxide (r = ?0.33, P < 0.0001). Change in the UCSD SOBQ at 12 months correlated in the expected direction with change in the HAQ DI (r = 0.54, P < 0.0001) and change in the SF‐36 PCS (r = ?0.44, P < 0.0001). Multivariate analysis adjusting for age, sex, and race identified male sex as a significant predictor of death (odds ratio [OR] 7.00, 95% confidence interval [95% CI] 1.55–31.76), while the UCSD SOBQ showed a strong trend toward significance (OR 1.82, 95% CI 0.97–3.41).

Conclusions

The UCSD SOBQ demonstrates good construct validity and responsiveness to change in SSc patients with pulmonary vascular disease.

     

Development and validation of Cedars‐Sinai Health‐Related Quality of Life in Rheumatoid Arthritis (CSHQ‐RA) short form instrument

Objective

To develop an abridged version of the 33‐item Cedars‐Sinai Health‐Related Quality of Life in Rheumatoid Arthritis instrument (CSHQ‐RA) and test the validity and reliability of the abridged instrument.

Methods

Items from the original 33‐item, 5‐domain CSHQ‐RA were assessed using psychometric and regression analyses of survey responses from 274 patients with rheumatoid arthritis. Items were retained in the final instrument based on statistical analysis and evaluation by an expert panel. Test‐retest reliability, internal consistency, convergent and discriminant validity, and ceiling and floor effects were examined for the shortened CSHQ‐RA.

Results

Statistical analysis and expert assessment yielded an 11‐item instrument including questions in 4 domains. Test‐retest reliability and internal consistency were high and the instrument showed good convergent and discriminant validity.

Conclusion

The abridged CSHQ‐RA short form is a valid and reliable instrument that can be used to examine the impact of RA on patients' health‐related quality of life. Prospective validation in clinical trial settings is warranted.

     

Health‐related quality of life of patients with psoriatic arthritis: A comparison with patients with rheumatoid arthritis

Objective

To compare health‐related quality of life (QOL) between patients with psoriatic arthritis (PsA) and patients with rheumatoid arthritis (RA), using the Medical Outcomes Study Short Form health survey (SF‐36) and the Health Assessment Questionnaire (HAQ).

Methods

Both the SF‐36 and the HAQ were administered to 107 PsA patients attending the University of Toronto Psoriatic Arthritis Clinic between January 1 and December 31, 1994, and to 43 RA patients attending a University of Toronto–affiliated RA clinic during the same period. Standardized assessments of disease activity and severity were also performed at each clinic visit. Logistic regression analysis was used to compare health‐related QOL between PsA and RA.

Results

Both patient populations experienced lower physical health compared with that of a general population sample. The RA patients demonstrated more active inflammatory disease at the time of assessment than the PsA patients. The PsA patients were younger, and more were men. Logistic regression analyses showed that patients with PsA reported higher levels of vitality than patients with RA, even after adjusting for the observed differences in clinical and demographic characteristics. PsA patients, however, reported more role limitations due to emotional problems and more bodily pain after adjusting for the difference in vitality and other covariates.

Conclusions

Although both patient populations experienced reduced QOL, there were some meaningful differences in how the 2 conditions affect health‐related QOL. Further, it appeared that there may be unique disabilities associated with the psoriasis dimension of PsA.