Background/Purpose: In knee osteoarthritis (OA) strengthening exercise improves pain and physical function, however a marked decline in exercise adherence has limited the long term efficacy of exercise.  Adherence drops precipitously when trainer instruction and social support for exercise are withdrawn.  We developed an interactive automated telephone calling system, Boston Osteoarthritis Strengthening telephone linked-communication (BOOST TLC), that provides low cost trainer instruction and behavioral counseling to motivate people with knee OA to continue strength exercises after participating in a group class. We tested the effect of BOOST TLC on exercise adherence over 24-m in a randomized trial.     

Methods: Participants were recruited from the community and had painful, self-reported doctor-diagnosed knee OA.  Participants initially completed a 6-week trainer led strength class using a protocol previously shown to improve pain and function in knee OA. The protocol included exercises for warm-up, posture, functional strength (squats and stair stepping), isolated knee strength with ankle weights (knee flexion and knee extension), hip abduction, core, and stretching.  The instruction emphasized proper form and progressive resistance training.  After completing the class, participants were randomized to BOOST TLC or control. BOOST TLC is an automated, interactive conversation system that asks questions, comments on responses, and educates and counsels users.  TLC stores the question responses in a database to direct current and future TLC conversations and provides alerts and reports to staff.  The BOOST TLC group received biweekly calls for 6-m and monthly calls for the subsequent 18-m.  The control and BOOST TLC group received an automated monthly phone message encouraging continued strength training.  The primary outcome was self-rated adherence to the strength exercises in the previous 3 months (from Ônot at allÕ to Ôcompletely as instructedÕ) on a 10-point scale.  Evaluations occurred at 6-m, 12-m, 18-m and 24-m after the strength class.  Secondary outcomes included WOMAC pain and physical function. 24-m adherence was analyzed using nonparametric Wilcoxon test and adjusted for baseline WOMAC pain using robust generalized estimating equations regression.

Results: There were 104 trial participants (82% female; 65 ± 8 years old; BMI 31 ± 7).  The 24-m treatment difference in adherence was not statistically significant (Boost TLC 3.5 ± 3.3, control 4.0 ± 3.5, p= 0.53), and remained non-significant when adjusted for baseline pain (p=0.46). There was no 24-m treatment difference in WOMAC pain (Boost TLC 4.6 ± 3.7, control 4.3 ± 3.7, p= 0.68) or physical function (Boost TLC 12.3 ± 9.7, control 12.8 ± 11.7, p= 0. 0.82).

Conclusion: BOOST TLC provided no additional benefit for exercise adherence above that provided by an automated, non-interactive message reminding participants to exercise.