Identifying the active components through the behaviour change techniques taxonomy in complex interventions for people living with multiple long‐term health conditions: A systematic review

More older adults are living with multiple long-term conditions (M-LTCs). Understanding the 'active components' of complex interventions to manage these is challenging. The Behaviour Change Techniques Taxonomy (BCTTv1) helps identify the 'active components' to understand which are associated with improved outcomes. This is important for people with M-LTCs due to health complications, competing health care regimes and conflicting clinical teams, requiring complex decision-making. This systematic review explores which BCTs are associated with effective complex interventions in people with M-LTCs. Five databases were systematically searched to identify RCTs evaluating behaviour change intervention effectiveness in people with M-LTCs, published between 1999 and 2025. Data on intervention characteristics, effectiveness and BCTs were synthesized. A BCT index of potential was calculated by determining the percentage of studies that used a BCT that had a positive primary outcome. To be considered to have potential, a BCT had to have an index of potential higher than 50%. Fifty-nine eligible articles were included. 44/93 possible BCTs were identified, ranging from 1 to 16 different techniques per intervention (mean = 7). Thirty-two BCTs were present in three or more studies, of which 17 had the potential to improve outcomes, such as behavioural goal setting, monitoring outcomes, problem solving and providing information about health and emotional consequences. Interventions designed for people with both physical and mental LTCs were more likely to contain BCTs with higher potential. Interventions delivered to those living with M-LTCs should incorporate relevant BCTs with a high index of potential and use mechanisms of action to identify other BCTs to include alongside these.