IntroductionThe sustainability of healthcare delivery systems is challenged by ageing populations, complex systems, increasing rates of chronic disease, increasing costs associated with new medical technologies and growing expectations by healthcare consumers. Healthcare programmes, innovations and interventions are increasingly implemented at the front lines of care to increase effectiveness and efficiency; however, little is known about how sustainability is conceptualised and measured in programme evaluations.ObjectivesWe aimed to describe theoretical frameworks, definitions and measures of sustainability, as applied in published evaluations of healthcare improvement programmes and interventions.DesignSystematic integrative review.MethodsWe searched six academic databases, CINAHL, Embase, Ovid MEDLINE, Emerald Management, Scopus and Web of Science, for peer-reviewed English journal articles (July 2011–March 2018). Articles were included if they assessed programme sustainability or sustained outcomes of a programme at the healthcare system level. Six reviewers conducted the abstract and full-text review. Data were extracted on study characteristics, definitions, terminology, theoretical frameworks, methods and tools. Hawker’s Quality Assessment Tool was applied to included studies.ResultsOf the 92 included studies, 75.0% were classified as high quality. Twenty-seven (29.3%) studies provided 32 different definitions of sustainability. Terms used interchangeably for sustainability included continuation, maintenance, follow-up or long term. Eighty studies (87.0%) clearly reported the timepoints at which sustainability was evaluated: 43.0% at 1–2 years and 11.3% at <12 months. Eighteen studies (19.6%) used a theoretical framework to conceptualise or assess programme sustainability, including frameworks that were not specifically designed to assess sustainability.ConclusionsThe body of literature is limited by the use of inconsistent definitions and measures of programme sustainability. Evaluations of service improvement programmes and interventions seldom used theoretical frameworks. Embedding implementation science and healthcare service researchers into the healthcare system is a promising strategy to improve the rigour of programme sustainability evaluations.