A Decade of Kaizen-Driven Asthma Reduction Through Integrated Clinical and Environmental Interventions in Kuwait Primary Care: An Interrupted Time-Series Evaluation

Asthma affects approximately 262 million people globally and imposes a disproportionate burden in arid Gulf states, where dust storms, traffic emissions, and extreme heat compound clinical management challenges. In Kuwait, adult asthma prevalence reaches 15% and annual direct healthcare costs exceed USD 208 million, yet standardised primary care protocols and environmental surveillance remain underdeveloped. In 2014, the primary care center’s catchment in Yarmouk, Kuwait’s first WHO-designated Healthy City, recorded an asthma incidence of 549.8 per 1,000 residents. Root-cause analysis identified absent clinical protocols, no spirometry access, untrained staff, and no integration of air-quality data with clinical workflows. A Kaizen-driven quality improvement programme was implemented over ten years (2014–2024) using iterative Plan–Do–Check–Act cycles. Clinical interventions included standardised asthma management protocols aligned with GINA guidelines, spirometry deployment, and staff training. Environmental interventions included traffic redirection via a highway underpass, green-space expansion, and progressive integration of real-time air-quality feeds into clinical decision support. The primary outcome—annual asthma incidence per 1,000 residents derived from the national Primary Care Information electronic health record system—was evaluated using segmented regression interrupted time-series analysis with autoregressive correction. Asthma incidence declined from 549.8 to 173.5 per 1,000 residents (−68.4%), with case counts falling from 5,498 to 1,822 (−66.9%). The pre-intervention trend showed rising incidence (β = +207.6/year, p = 0.019). Following the 2015 clinical intervention, the slope reversed significantly (β = −239.4/year, p = 0.011). A temporary rebound after 2022 coincided with post-pandemic normalisation, followed by resumed decline after environmental data integration. The model explained 89% of variance (R² = 0.89). Integrating Kaizen-based clinical quality improvement with environmental health interventions achieved a sustained, near-70% reduction in asthma incidence over a decade. This model offers a transferable framework for primary care systems in high-burden, environmentally challenged settings.