Background Health Assessment Questionnaire-Disability Index (HAQ-DI) is a self-report of physical function already validated as a measure of physical disability in patients with systemic sclerosis (SSc) (1). No previous studies have examined the impact of comorbidities in SSc patients on physical function as assessed by HAQ-DI.
Objectives The aim of this study was to investigate whether comorbidities could influence the HAQ-DI in SSc patients.
Methods 313 consecutive SSc patients admitted to our centre between 2000 and 2011were investigated for clinical and serological subset, disease duration, disease activity (2), extent and severity of organ involvement (3), HAQ-DI and comorbidities. The comorbidities were collected using the Functional Comorbidity Index (FCI) (4). Patients with overlap syndrome were excluded from the analysis. Complete data were available in 291 patients and included in the study. Correlations were calculated using Spearman’s rank correlation test. Mann-Whitney test was used to perform comparison between groups. To assess the effects of comorbidities on physical disability multiple linear regression analysis was performed including age, sex, disease activity and total disease severity. P<0.05 was considered statistically significant. Data were analysed using SPSS18 software.
Results The study included 259 females. The mean age was 48.56 years (SD=14.36), the median HAQ-DI 0.125 (range=0-2.75), the mean FCI 06 (SD 0.79). In univariate analysis HAQ-DI was found to be significantly correlated with age (P<0.0001), disease activity (P<0.0001), total disease severity (P<0.0001), FCI (p=0.0056) and not correlated with disease duration. HAQ-DI was significantly higher in patients with FCI >0 when compared with patients without comorbidities (i.e. FCI=0, P=0.0094). When adjusted for sex, disease activity and severity, HAQ-DI was still found to be independently associated with FCI (P=0.034). When age was added in the model, FCI was not independently associated any more. This is consistent with an increased morbidity correlated with age (p<0.0001).
Conclusions Our data suggest that comorbidities significantly influence and represent an additional burden to the physical disability of SSc patients. This aspect should be considered for the clinical care and assessment of disability in SSc patients. Further studies including different diseases are needed to clarify the effect of other comorbidities on physical function in these patients.
Steen VD, Medsger TA Jr. Arthritis Rheum 1997.
Valentini G et al. Ann Rheum Dis 2001.
Medsger TA Jr et al. Clin Exp Rheumatol. 2003.
Groll D et al. J Clin Epidemiol 2005.
Disclosure of Interest None Declared