The SupportBack 2 randomised controlled trial (RCT) compared the clinical and cost-effectiveness of an internet intervention supporting self-management versus usual primary care in reducing low back pain (LBP)-related disability. In this study, we aimed to identify and understand key processes and potential mechanisms underlying the impact of the intervention.

This was a nested qualitative process evaluation of the SupportBack 2 RCT (ISRCTN: 14736486 pre-results).

Primary care in the UK (England).

46 trial participants experiencing LBP without indicators of serious spinal pathologies (eg, fractures, infection) took part in telephone interviews at either 3 (n=15), 6 (n=14) or 12 months (n=17) post randomisation. Five physiotherapists who provided telephone support for the internet intervention also took part in telephone interviews.

An internet intervention ‘SupportBack’ supporting self-management of LBP primarily through physical activity and exercise delivered in addition to usual care, with and without physiotherapist telephone support.

Data were analysed thematically, applying a realist logic to develop context-mechanism-outcome configurations.

Four explanatory themes were developed, with five context-mechanism-outcome configurations. Where benefit was reported, SupportBack appeared to work by facilitating a central associative process where participants linked increases in physical activity or exercise with improvements in LBP, then continued to use physical activity or exercise as key regulatory strategies. Participants who reported little or no benefit from the intervention appeared to experience several barriers to this associative process, including negative expectations, prohibitive beliefs about the cause of LBP or functional limitations preventing engagement. Physiotherapists appeared to provide accountability and validation for some; however, the remote telephone support that lacked physical assessment was viewed as limiting its potential value.

Digital interventions targeting physical activity and exercise to support LBP self-management may rely on mechanisms that are easily inhibited in complex, heterogeneous populations. Future research should focus on identifying and removing barriers that may limit the effectiveness of digital self-management support for LBP.

Increasing physical activity and effectively managing stress can positively impact immunity and may reduce the duration of respiratory tract infections (RTIs). As part of a larger trial, participants accessed a digital behavioural change intervention that encouraged physical activity and stress management to reduce RTIs. We aimed to understand the barriers and facilitators to engaging in physical activity and stress reduction.

A qualitative process analysis from semistructured interviews of the behavioural intervention in a randomised control trial.

Primary care in the UK.

34 participants (aged 18–82 years) in the behavioural intervention arm.

The larger trial involved four interventions: a gel-based antiviral nasal spray; a saline water-based nasal spray; a behavioural intervention; usual care. In this study, we focused on participants allocated to the behavioural intervention. The behavioural intervention included two components: one to increase physical activity (getting active) and another for stress management techniques (healthy paths) to reduce RTIs.

We analysed the interviews using thematic analysis with a critical realist perspective (focusing on). We developed five themes: digital intervention engagement, views on intervention allocation, the role of getting active, the role of healthy paths and benefits reinforcing behaviour. Participants’ views on the relevance and benefit of the behavioural intervention shaped their engagement with the intervention website and behaviour. Facilitators of intervention engagement included awareness of inactivity, goal setting, increasing immunity, positive outcome expectations and benefits from changing behaviour. Barriers to engagement included negative outcome expectations, such as around efficacy of the behaviours.

Overall, the results highlighted the importance of positive expectations for a digital intervention promoting physical activity and stress management for RTI reduction. Future interventions should consider how to clearly communicate a broad range of perceived benefits to users.

The trial was prospectively registered with International Standard Randomized Controlled Trial Number (ISRCTN) registry (17936080).