Using the Implementation Leadership Scale (ILS) for nutrition incentive programs in the food retail context

The Implementation Leadership Scale (ILS) is widely used to measure implementation leadership for health innovations. While used often in behavioral health and other clinical settings, it remains untested in community public health contexts such as food retail. Healthy food retail strategies, including nutrition incentive programs, could benefit from measuring and subsequently strengthening leadership support to facilitate effective implementation. The objective of this study was to test the suitability of an adapted ILS to measure leadership support for a nutrition incentive program implemented in a brick-and-mortar food retail setting.

As part of a larger evaluation, a multidisciplinary team of practitioners, evaluators, and food retail representatives created a modified version of the ILS suitable for the food retail context. Food retailer staff and management from one privately-owned grocery chain who participated in implementing a nutrition incentive program for Supplemental Nutrition Assistance Program (SNAP) shoppers in Southern California completed a survey that included the adapted ILS. Of the 522 survey respondents from the larger evaluation, 473 retailers including management and staff provided complete responses for the ILS. We assessed construct validity, internal consistency reliability, and measurement invariance using differential item functioning (DIF) analyses, Cronbach's alpha, confirmatory factor analysis (CFA), and multiple-group CFA for the adapted ILS.

DIF analyses indicated minimal evidence of measurement bias. The CFA supported the original four-factor ILS structure, with excellent internal consistency for the knowledgeable, supportive, and perseverant subscales and fair consistency for the proactive subscale. Further, the demonstrated measurement invariance between management and staff highlights the robustness of the ILS and its potential for assessing alignment or discrepancies in perceptions of implementation leadership between management and staff within food retail organizations.

Findings suggest that the adapted ILS is a valid and reliable tool for measuring implementation leadership support for nutrition incentive programs in a food retail setting in the US. Future research should examine the adapted ILS across diverse food retail environments and healthy food retail strategies to improve its generalizability and applicability.