Background: This mixed-methods dissertation examined the implementation and costs of guideline-based biopsychosocial (BPS) management of low back pain (LBP) in Finnish occupational health primary care (OHPC). A multifaceted implementation strategy was used, combining training and booster sessions with materials, clinical champions, and outreach visits. We aimed to 1) evaluate the quality of LBP management by applying predefined criteria to physiotherapists’ documentation; 2) analyze the effects of the intervention on OHPC resource utilization and work absenteeism compared to usual care; 3) examine how capabilities, opportunities, and motivation influence the implementation of guideline-based BPS management of LBP, as perceived by occupational healthcare professionals and 4) tailor a shortened version of The Determinants of Implementation Behavior Questionnaire (DIBQ) to multiprofessional rehabilitation context and cross-culturally adapt a Finnish language version.

Methods: The cluster-randomized trial (ISRCTN11875357) included six national OHPC providers, with 27 units randomized into intervention and control arms. In the intervention arm, physiotherapists and physicians received targeted 3-to-7-day training in guideline-based BPS management in 2017 and 2018, while the control arm continued usual care.

Study I evaluated the quality of LBP care from physiotherapists’ first-visit documentation using predefined quality criteria applied to electronic patient records. In total, 98 records documented by 28 physiotherapists from intervention and controls arms were analyzed.

Study II analyzed healthcare utilization and LBP-related sick leave data collected from electronic patient records over a one-year follow-up for 232 patients in the intervention arm and 80 control arm patients. Costs were estimated using linear mixed models by multiplying unit costs (in euros) by each type of OHPC resource use including visits to physicians, physiotherapists, nurses, imaging and sick leave.

In Study III, focus group interviews (n=12) were conducted one year after the educational intervention. with physicians, physiotherapists and nurses (n=51) treating patients with LBP in occupational healthcare teams. The data were analyzed using deductive and inductive content analysis informed by the Capability, Opportunity, Motivation, Behavior (COM-B) model.

In Study IV, the cross-cultural translation of English DIBQ to Finnish was followed by a two-round Delphi survey involving experts in multiprofessional rehabilitation including physicians, physiotherapists, occupational therapists, psychologists, nursing scientists, social scientists. Altogether, 25 experts participated in Round 1, and 21 in Round 2. Participants rated the importance of each DIBQ item for inclusion in the final scale on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Consensus to include an item was defined as a mean score of at least 4 by ≥75% of Delphi participants. Open-ended comments were analyzed inductively. Item- and scale-level content validities were assessed using the content validity index.

Results: Training in guideline-based BPS management was associated with more frequent documentation of behaviors aligned with high-quality LBP care at physiotherapists’ first visit in OHPC compared to usual care.

The multiprofessional training intervention shifted care from physician-led management toward a multiprofessional, physiotherapist-driven model without increasing total costs over 12 months (€-1908, 95% CI €-6734–2919).

Facilitators of implementation were mainly related to increased capability and motivation. Participants reported improved confidence on their own and the teams’ capabilities on treating more challenging patients in OHPC, enhanced communication skills, a broader understanding of the multidimensional nature of LBP, and a strengthened professional role. Barriers were related to opportunities at the organizational and system levels, including limited time and resources, unclear care pathways, inconsistent team agreements, and structural constraints.

In the cross-cultural adaptation process, consensus was reached after Round 2 on the inclusion of 21 items in the multiprofessional DIBQ (DIBQ-mp). The final version covers 11 Theoretical Domains Framework domains. Item-level content validity indices were at least 0.78, and the scale-level content validity index average was 0.93, indicating excellent content validity for multiprofessional rehabilitation context.

Conclusion: Although the BPS training intervention improved the quality of LBP assessment and management, influenced OHPC resource allocation, and strengthened professionals’ capabilities and motivation, implementation into routine practice remained incomplete at 12-month follow-up. Complementary implementation strategies for sustained organizational support and clear care pathways should be further developed to embed BPS management in occupational health practice. The DIBQ-mp appears to be a promising tool for evaluating implementation determinants in multiprofessional guideline-based rehabilitation interventions.