Relating process evaluation measures to complex intervention outcomes: findings from the PACE-UP primary care...

Area of Science:

• Public Health
• Intervention Science
• Behavioral Medicine

Background:

• The PACE-UP trial showed a pedometer-based walking intervention improved physical activity (PA) in primary care patients aged 45-75.
• The intervention included postal and nurse-supported arms.
• This study explored how process evaluation measures related to changes in PA outcomes.

Purpose of the Study:

• To investigate the association between process evaluation measures and changes in objective physical activity outcomes.
• To determine the role of intervention adherence (dose delivered, fidelity) in the effectiveness of a pedometer-based walking intervention.

Main Methods:

• Utilized the Medical Research Council (MRC) framework for process evaluation.
• Employed multi-level models to assess the impact of nurse session attendance, PA diary completion, and pedometer use on PA outcomes.
• Measured changes in daily step-counts and time spent in moderate-to-vigorous physical activity (MVPA) in bouts.

Main Results:

• Higher attendance at nurse sessions was linked to significant increases in daily steps and MVPA at 3 and 12 months.
• Diary completion showed strong positive associations with increased steps and MVPA at 3 months, with effects persisting in the postal group at 12 months.
• Regular pedometer use in the postal group was associated with higher steps and MVPA at both time points.

Conclusions:

• Process evaluation measures were significantly associated with physical activity outcomes, indicating their importance in intervention success.
• While causality cannot be inferred, adherence to intervention components like nurse support and diary completion appears crucial.
• The MRC framework proved effective for evaluating intervention implementation.