Development of hand phenotypes and changes in hand pain and problems over time in older people.

Hand disabilities are frequent causes of pain and disability in older people, yet knowledge regarding the characteristics and patterns of hand pain and problems over time is lacking. The main aim of this study was to identify subgroups of older individuals with distinct presentations (phenotypes) of hand pain and function, investigate how these might change over a 6-year period, and explore what characteristics and factors are associated with long-term status. The study population stemmed from the North Staffordshire Osteoarthritis Project, a large, general population-based, prospective, cohort study of adults aged 50 years and older. Information on hand pain and problems was collected using questionnaires at baseline, 3 years, and 6 years. Overall, 5617 participants responded at all time points and were included in the analysis. Five phenotypes were identified using latent transition analysis ("least affected," "high pain," "poor gross function," "high pain and poor gross function," and "severely affected") based on 8 hand pain and functional items. The most common transition between phenotypes was from "high pain" at baseline to "least-affected" group. There was a high level of stability in individuals in the "least-affected" or "severely affected" group at baseline. Individuals with widespread body pain, nodes, sleep problems, and pain in both hands at baseline were more likely to be in a severe hand phenotype at 6 years. The results provide clinically relevant information regarding the pattern of hand pain and problems over time and factors that predict transition to more severe hand phenotypes.