Abstract
Purpose: :
The 64 item long-form Profile of Fatigue and Discomfort-Sicca Symptoms Inventory (PROFAD-SSI) was developed as a measurement tool for use in Primary Sjogren’s Syndrome (PSS) and other rheumatic disorders. It documents patient-reported symptoms of ocular, oral, cutaneous and vaginal dryness. Because of its length we subsequently developed a 19 item short-form version to enable more rapid assessment of patients in busy out-patient clinics. We now report a comparison between the two and also evaluate the feasibility of an even briefer version using visual analogue scales (VASs).
Methods: :
Questionnaire surveys comprising the long and short-form versions of the PROFAD-SSI were mailed to 43 patients with PSS and 50 patients with Rheumatoid Arthritis (RA) who completed them contemporaneously (T(time) = 0 months). Identical questionnaires were mailed to this cohort again after 1 month (T(time) = 1 month). PSS patients also completed a series of VASs comprising fatigue and sicca domains of the PROFAD-SSI. Spearman’s rho correlations were calculated for the relationships between the PSS and RA patients’ long and short-form PROFAD-SSI domain and total scores at both time points (T=0 and T=1 month) and also for VAS scores and domain and total scores for the short-form PROFAD-SSI. Confirmatory Principal Components Factor Analysis with Varimax Rotation and Cronbach’s alpha was used to evaluate the internal structure of the short-form PROFAD-SSI.
Results: :
Surveys were returned by 35/43 (81.4%) PSS and 35/50 (70%) RA patients. All domains of the long and short-form PROFAD-SSI strongly correlated (Spearman’s rho between 0.779 and 0.996, p<0.01). Factor analysis generally confirmed the previously validated domain structure (Cronbach's alpha = 0.99). The short-form PROFAD-SSI somatic fatigue domain correlated more strongly with the fatigue VAS than the mental fatigue domain (Spearman’s rho 0.769 and 0.548 respectively, p<0.01). The short-form SSI domain scores correlated closely with equivalent VAS scores (Spearman’s rho between 0.747 and 0.927, p<0.01).
Conclusions: :
The long and short-form PROFAD-SSI questionnaire scores correlate closely suggesting that the short form PROFAD-SSI is valid as an outcome tool. Preliminary data suggests that a still briefer format with compression of domains into single VASs is also feasible.
Keywords: cornea: tears/tear film/dry eye • quality of life • autoimmune disease