An Assessment of Grip Strength Measurement in Rheumatoid Arthritis

The intra-observer, inter-observer, day-to-day, week-to-week and diurnal variations in grip strength measurement have been studied in patients with rheumatoid arthritis. In addition, the changes in grip strength measurements in a double-blind, cross-over trial of Sodium Salicylate and Prednisolone are reported. An intra-observer error of up to 9 mmHg was found and, in addition, there was also considerable variation in grip strength measurements between different observers. Grip strength is responsive to Sodium Salicylate and Prednisolone therapy but the change in association with the former was minimal—indicating insensitivity of the test. In clinical trials, measurement of grip strength should not only be performed by one observer for each patient but measurements should be made at the same time of day because of its diurnal variation. The inherent errors in the method should be considered when interpreting results of grip strength measurement in such trials.