Background/Purpose: Although patients with early rheumatoid arthritis (RA) have substantially reduced grip strength compared to the general population, some improvement over time has been demonstrated in many patients. The objective of this study was to identify early predictors of future grip strength in patients with RA.

Methods: An inception cohort of patients with early RA (symptom duration ≤12 months), recruited in 1995-2005, was investigated and followed in a structured program (4 examinations over 5 years), including clinical evaluation and grip force measurement. Grip force was measured using the electronic instrument Grippit (AB Detektor, Gothenburg, Sweden). Average grip force values of the dominant hand were evaluated at each visit, and compared to the expected, based on age- and sex-specific reference values from the literature. Patients in each of the three higher quartiles of baseline disease activity (DAS28), disability (HAQ), pain (visual analogue scale, VAS) and patient global assessment (VAS global) were compared to the lowest quartile. Differences in percentage of expected grip force values over the study period, and differences in change over time, were estimated using mixed linear effect models.

Results: A total of 233 patients with early RA (70 % women, mean age 60.5 years, median symptom duration 7 months) were investigated. The mean value for the average grip force of the dominant hand increased from 40 % of expected at baseline to 57 % at the 5-year follow-up. Patients with baseline parameters in the three higher quartiles had significantly lower mean grip force values over time, compared to the lowest quartiles (Table). Patients in the highest quartile of DAS28 had significantly greater improvement compared to the lowest quartile (estimated difference in change per year 3.1 % of expected; 95 % CI 1.4 to 4.9). By contrast, there was no difference in improvement for those in the highest quartiles of VAS pain (estimated difference in change per year 0.5 % of expected; 95 % CI -1.3 to 2.3) or VAS global (Table), compared to those in the lowest quartiles.

Conclusion: Patients with a severe disease phenotype at baseline had particularly impaired grip force over the first 5 years after RA diagnosis. However, those with high initial disease activity experienced greater improvement in grip force, likely due to successful treatment. By contrast, poor patient reported outcomes at baseline were associated with persistent impairment of grip strength.