Chronic obstructive pulmonary disease (COPD) describes types of obstructive lung diseases characterized by long-term breathing problems and poor airflow. Since COPD is a progressive disease an early identification and prevention of causes is critical. The progression of COPD can only be slowed down or in the best case stopped; a cure is not available yet. COPD exacerbations describes drastically worsening of symptoms and are likely leave behind permanent, irreversible lung damage. Following a diagnosis through a GP, also the management and follow-up treatment of COPD is done by GPs. Where current guidelines are based on clinical trials evaluating the effectiveness of medical treatment of COPD, it is unknown how effective real world primary care COPD management is on future health outcomes of the patients.
The aim is to estimate causal effect sizes of primary care COPD management on critical outcomes such as COPD exacerbations and hospital admissions. For the patients wellbeing and the financial burden on the health system, an early slowdown of COPD progression is critical. Further the large sample size in CPRD will allow to study potential variations in effect sizes between patient groups, based on smoking habits, sex or age. In a socio-economic perspective effect size variations will be evaluated for deprivation differences. Inequality in prevalence with respect to deprivation is well known for COPD, but not for potential benefits through COPD management.
Given the promising early COPD management effects, the results of this study have direct implications for clinical care and population health.
This study seeks to measure the effect of primary care COPD management on short-, mid-, and long-term clinical outcomes (progression of COPD, exacerbations, mortality, emergency hospitalizations, major adverse health events) in a routine care set-up for adult men and adult women. To establish causality, we make use of a regression discontinuity (RD) design taking advantage of public health guidelines on confirming a COPD diagnosis by a FEV1/FVC ratio lung function test. Following a COPD diagnosis, disease management is done by GPs. Because physicians base their diagnosis decisions on additional considerations besides public health thresholds, we use an instrumental variable approach that is robust to partial compliance. We evaluate the robustness of results by gradually narrowing down the bandwidth around the treatment threshold and thus only including patients with FEV1/FVC ratios increasingly close to the treatment threshold level. In addition, we will test for heterogenous treatment effects by stratifying our sample by medication applied, sex, age, ethnicity, socioeconomic status, urban vs rural place of residence, and comorbidities. The findings of this study are expected to provide novel insights into the effectiveness COPD management in a real-life setting and can directly inform clinical practice.
Health Outcomes to be Measured:
Primary outcomes (all to be measured over time horizons of six months, one year, three years, five, and ten years):
COPD exacerbations (bronchitis and chest infections for not yet diagnosed patients); frequencies and severity of incidents; hospitalizations related to COPD and likely COPD exacerbations; smoking cessation (among smokers); all-cause mortality; mortality related to COPD (Respiratory and heart failure)
2011 Rural-Urban Classification at LSOA level;HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation