EUROQOL-reported health disability demonstrates reduced quality of life remaining constant over time in established psoriatic arthritis

Background: Psoriasis (PsO) and Psoriatic arthritis (PsA) are known to have a significantly detrimental effect on health related quality of life (HRQoL). The EuroQol (EQ5D) has been used in a number of PsA clinical trials, distinguishes well across levels of PsA severity, and demonstrates utility gain in patients started on anti-TNF therapy within the first few weeks, sustained over time. Our objective was to measure health related quality of life in PsA using the EQ5D and assess change over time; dependent on age, gender, disease duration and anti-TNF treatment. Methods: The EQ5D is a self reported questionnaire describing health-related quality of life consisting of five descriptive questions (EQ5D) converted into a single summary index using UK valuation index and a visual analogue scale (EQ5Dvas) from 100 as best imaginable health and 0 worst imaginable health. 520 patients were sent EQ5D questionnaires at six month intervals between 1/2008 and 1/2010. 317 patients returned questionnaires. 287 patients completed the EQ5D fully on at least one time point. 184 patients completed EQ5D at two or more time points. HAQ was available for 173 patients and DLQI for 24 patients. The first and last questionnaires were compared, mean interval 1.2yrs (443 days, range 4-882). Comparisons over time were made with paired t test or Wilcoxon rank as appropriate. Correlations were performed using the Pearson correlation coefficient. Results: Of the 287 patients the mean age was 66yrs (median 70, range 20-86), 50.2% male (n = 144) 49.8% female (n = 143) and disease duration mean 16.9yrs (range 0-57yrs). The mean EQ5Dvas was 68.1 (Standard Deviation 23, Standard Error of Mean 1.3), male 68.8 (SD 23.4 SEM 1.9), female 67.5 (SD 28.8, SEM 1.9). Results of the 184 patients who completed questionnaires at two time points are reported in Table 1. HAQ (Minimally Important Difference [MID] 0.22) and DLQI (MID between 2.2 and 3.1) demonstrated statistical but not clinically significant improvement. There was no change in EQ5D or EQ5Dvas over time between age, gender, disease-duration or anti-TNF treatment. EQ5Dindex demonstrated good correlation with the HAQ (-0.56) and DLQI (r = −0.59) significant at p < 0.01. Conclusions: Health related quality of life as measured with the EQ5D and HAQ demonstrates reduced quality of life in PsA patients and this impairment remains constant over time irrespective of age, gender, disease-duration or therapy. However, our study will not have captured early phase improvement following treatment initiation that we are now studying prospectively.