Effect of an implementation support program aimed at an evidence-based physical healthcare model for patients with severe mental illness

Background Patients with severe mental illness (SMI) experience higher rates of morbidity and mortality from physical conditions, particularly cardiovascular disease, due to modifiable risk factors and inadequate healthcare. This study aimed to assess whether an implementation support program, directed at a model for evidence-based physical healthcare, effectively improved fidelity and subsequently patient outcomes compared to no such support. Methods In this multicentre study on the implementation of national clinical guidelines for physical health care for patients with SMI, 26 clinical sites within specialist mental health services in Norway participated between June 2016 to April 2018. Thirteen sites received implementation support, while the remaining thirteen did not. Fidelity to the evidence-based model for physical healthcare was measured using The Physical Health Care Fidelity Scale. Fidelity assessments and data from 230 patients across these sites were collected at baseline, 12 months, and 18 months. Changes in fidelity scores and outcome variables (cardiovascular risk factors and received evidence-based treatment of physical healthcare) from baseline to follow-up were analyzed using generalized linear mixed models. Results Clinical sites showed consistently low mean fidelity scores, but those with implementation support had greater improvements (mean increase of 0.9 vs. 0.2). Higher fidelity was associated with increased odds for patients receiving physical activity and somatic healthcare interventions (OR 1.73, 95% CI (1.10; 2.72) and OR 1.52, 95% CI (1.07; 2.17), respectively). Smoking cessation interventions significantly increased at intervention sites from baseline to 12 months (OR 4.32, 95% CI (1.28; 14.57)), and by 18 months, somatic healthcare interventions were more common at sites with implementation support (OR 6.13, 95% CI (1.84; 20.37)). Cardiovascular risk factors in participants were not associated with fidelity. Conclusion Clinical sites receiving extensive implementation support demonstrated promising improvements in overall fidelity scores compared to those that did not. However, no associations were identified between fidelity and patient outcomes. Fidelity scores remained low across all included sites, reflecting a generally limited implementation of evidence-based physical healthcare. This highlights the need to employ standardized fidelity scale measures to empower the specialist mental health system to identify areas requiring improvement and guide future interventions. Trial registration The trial was retrospectively registered in ClinicalTrials.gov 31.08.2017, ID: NCT03271242.