Importance: A combination of conservative treatments is commonly used in clinical practice for thumb base osteoarthritis despite limited evidence for this approach.
Objective: To determine the efficacy of a 6-week combination of conservative treatments compared with an education comparator.
Design, setting, and participants: Randomized, parallel trial with 1:1 allocation ratio among people aged 40 years and older with symptomatic and radiographic thumb base osteoarthritis in a community setting in Australia.
Interventions: The intervention group (n = 102) received education on self-management and ergonomic principles, a base-of-thumb splint, hand exercises, and diclofenac sodium, 1%, gel. The comparator group (n = 102) received education on self-management and ergonomic principles alone. Intervention use was at participants' discretion from 6 to 12 weeks.
Main outcomes and measures: Hand function (Functional Index for Hand Osteoarthritis; 0-30) and pain (visual analog scale; 0-100 mm) were measured at week 6 (primary time point) and week 12. An α of .027 was used at week 6 to account for co-primary outcomes.
Results: Of the 204 participants randomized, 195 (96%) and 194 (95%) completed follow-ups at 6 and 12 weeks, respectively; the mean (SD) age of the population was 65.6 (8.1) years, and 155 (76.0%) were female. At week 6, hand function improved significantly more in the intervention group than the comparator (between-group difference, -1.7 units; 97.3% CI, -2.9 to -0.5; P = .002). This trend was sustained at 12 weeks (-2.4 units; 95% CI, -3.5 to -1.3; P < .001). Pain scores improved similarly at week 6 (between-group difference, -4.2 mm; 97.3% CI, -11.3 to 3.0; P = .19). At week 12, pain reduction was significantly greater in the intervention group (-8.6 mm; 95% CI, -15.2 to -2.0; P = .01). There were 34 nonserious adverse events, all in the intervention group-mostly skin reactions and exercise-related pain exacerbations.
Conclusions and relevance: In this randomized clinical trial of people with thumb base osteoarthritis, combined treatments provided small to medium and potentially clinically beneficial effects on hand function but not pain.
Trial registration: Australian New Zealand Clinical Trials Registry Identifier: ACTRN12616000353493.