Stefan Elbers

185 AGRIPPA: protocol for an RCT Table 1. Planned Outcome Domains, Outcome Measures, and Statistical Methods. Outcome Hypothesis/research question Outcome measure Method of analysis Primary Self-perceived pain disability The development of pain disability over time after IMPT a will be more favorable for the enhanced treatment condition compared to usual care. PDI b,c Multilevel analysis Planned subgroup analysis on patients that scored 1 (“very much better”) or 2 (“much better”) on the GPE d scale at t 1 e . For patients that experienced meaningful treatment success, the development of pain disability over time after IMPT will be more favorable for the enhanced treatment condition compared to usual care. 1. PDI c 2. GPE f Multilevel analysis Secondary (quality of life) Health care costs The enhanced treatment condition will be cost-effective compared with usual care at 3 and 6 months posttreatment. 1. SF-12 f,g 2. iPCQ f,h Cost- effectiveness analysis Illness perception The development of illness perceptions over time after IMPT will be more favorable for the enhanced treatment condition compared to usual care. IPQ-K DLV c,i Multilevel analysis Pain self-efficacy The development of pain self-efficacy over time after IMPT will be more favorable for the enhanced treatment condition compared to usual care. PSEQ c,j Multilevel analysis Pain intensity The development of outcome measures over time may be affected by the level of pain intensity NRS c,k Multilevel analysis Engagement and usability Overall engagement The level of engagement and usability will be positively associated with a change in pain disability during follow up ( t 4 l – t 1 ). 1. System usability scale f 2. System usage data of AGRIPPA app (see below) Multiple linear regression Frequency of engagement How does the frequency of engagement vary over time after treatment? Average number of logins per week Descriptive statistics Depth of engagement How does the average number of features accessed per login vary after treatment? Average number of features accessed per log-in Descriptive statistics Duration of engagement How do the average minutes spent at each login as well as the total time spent with the app per week vary after treatment? 1. Average minutes spent at each login. 2. Total time spent with the app Descriptive statistics