Facilitating physical activity and reducing symptoms in patients with knee osteoarthritis: study protocol of a randomized controlled trial to test a theory-based PrevOP-psychological adherence program (PrevOP-PAP).

BACKGROUND: The present randomized controlled trial, which is crossed with the "PREVenting the impairment of primary Osteoarthritis by high impact long-term Physical exercise regimen" Main Medical Trial (PrevOP-MMT), aims to evaluate a psychological adherence program (PrevOP-PAP), and is designed to support persons with knee osteoarthritis (OAK) in the uptake and maintenance of regular physical activity to reduce OAK symptoms. The PrevOP-PAP is based on the Health Action Process Approach (HAPA), a social-cognitive theory predicting health behavior change in individuals, extended here by social network characteristics and social exchange processes. It is expected that participants with OAK receiving the PrevOP-PAP will maintain higher levels of regular physical activity throughout a 24-month period and consequently report lower levels of OAK symptoms than participants of an active control condition. METHODS: A total of N = 240 participants with medically verified moderate OAK will be randomly assigned to an intervention condition (PrevOP-PAP-I; 50%) or an active control condition (PrevOP-PAP-CTRL). The PrevOP-PAP-I includes a motivational intervention, repeated self-regulation interventions, and a network creation intervention delivered over 12 months. Modes of intervention delivery include a paper-pencil motivation leaflet with a quiz, a computer-assisted face-to-face intervention, four computer assisted phone-based interventions, and activity calendars. The PrevOP-PAP-CTRL includes the motivational intervention only. Primary outcome will be OAK symptoms. Secondary outcomes include objectively and subjectively measured physical activity and indicators of quality of life. Other outcomes are HAPA-derived self-regulatory indicators as well as proposed social network and social exchange mechanisms of health behavior change. Assessments take place at baseline, 6 months, 12 months, 18 months, and 24 months following baseline. DISCUSSION: Based on the extended HAPA, this study seeks to reveal the self-regulatory and social mechanisms of the uptake and maintenance of physical activity and their relation to disease symptoms in persons with OAK. The design and evaluation of this program are intended to become a yardstick for future development and implementation of digitalized psychological adherence programs in this population. TRIAL REGISTRATION: German Clinical Trials Register; also available at http://apps.who.int/trialsearch/ ; registration number: DRKS00009677 ; date of registration: 26 January 2016.

Augmenting fruit and vegetable consumption by an online intervention: Psychological mechanisms.

OBJECTIVE: Fruit and vegetable (FV) intake was examined among men and women who participated in an online intervention. The psychological constructs involved were outcome expectancies, behavioral intention, planning, and self-efficacy. One purpose of the analyses was the evaluation of a self-efficacy treatment component. The other purpose of the analyses regarded the role of psychological mechanisms that might be responsible for individual differences in the process of behavior change. DESIGN: A two-arm online intervention with a standard and an enhanced intervention group focusing on FV planning was conducted to improve FV intake, followed up at two and four weeks. The intervention groups differed by the additional inclusion of a self-efficacy ingredient in the enhanced intervention. Linear mixed models examined the intervention effects, and a longitudinal structural equation model explored which psychological constructs were associated with changes in FV intake. Participants were N = 275 adults of whom n = 148 completed the four-week follow-up. Their age range was 18-81 years (Mage = 32.50, SDage = 14.00). RESULTS: Analyses yielded an overall increase in self-reported FV intake. Moreover, a triple interaction between time, sex, and experimental groups on self-efficacy emerged, indicating that men, independent of treatment conditions, reported an increase in their confidence to improve FV intake, whereas women developed higher FV self-efficacy when being in the enhanced group instead of the standard group. Planning, self-efficacy, and intention mediated between outcome expectancies, and follow-up FV intake. CONCLUSION: Both intervention arms produced overall improvements in FV intake. The enhanced intervention resulted in a steeper increase in self-efficacy in women compared to men, and compared to the standard intervention. A psychological mechanism transpired that included a sequence leading from initial outcome expectancies via planning, self-efficacy, and intention towards FV intake.