Subclinical disability, the need for modifications in task performance or frequency without reported difficulty with the task, has been identified as a stage along the disability continuum. We estimated the prevalence of subclinical disability in valued life activities (VLAs) among individuals with rheumatoid arthritis (RA), identified characteristics of individuals with VLA subclinical disability, and estimated the ability of VLA subclinical disability to predict later decrements in functioning.
Data were from 3 years of a longitudinal panel study of individuals with RA, for which annual structured telephone interviews are conducted (n=508 in year 1, n=442 in year 3). Respondents rated difficulty in VLAs and then reported whether they used any of 4 behavioral modifications (limitations, extra time, help, or equipment) for each. Subclinical disability was defined for each VLA as no reported difficulty with use of any modification. Multiple regression analyses identified predictors of subclinical disability in year 1 and the role of year 1 subclinical disability in development of overt disability between year 1 and year 3.
Almost three-quarters of the subjects exhibited subclinical disability in at least 1 VLA in year 1. Duration of RA was consistently associated with subclinical disability. Individuals with subclinical disability at baseline were significantly more likely to experience increases in functional limitations (odds ratio [OR] 1.09, 95% confidence interval [95% CI] 1.01-1.18) and VLA disability (OR 1.14, 95% CI 1.06-1.23) over a prospective 2-year period.
Subclinical disability may be a valuable marker of individuals in a disability transition phase who are particularly susceptible to intervention that would enable them to maintain functioning.