Between-practice variation in chronic obstructive pulmonary disease diagnosis guideline compliance: database study.

Background: Early chronic obstructive pulmonary disease (COPD) diagnosis is vital, but little is known about compliance with relevant diagnostic guidelines or variation in primary care.

Aim: To quantify between-practice variations in guideline compliance and over time.

Design & setting: observational study in English primary care.

Method: The Clinical Practice Research Datalink was used to assess the use of four pre-diagnostic investigations (spirometry, chest X-ray, FBC and BMI) by GP practices for patients with COPD recorded first in primary care, in three time periods: 2006-7 (cohort 1), 2016-7 (cohort 2), and Mar-Aug 2020 (cohort 3). Multilevel logistic regression models quantified the non-random variation between GP practices in spirometry around diagnosis. Funnel plots counted the proportion of outliers.

Results: Cohort totals were 31 676 (cohort 1), 37 393 (cohort 2) and 3368 (cohort 3). Overall, the mean age was 68.3 years (SD 12.0), with 47.3% female. The use of pre-diagnosis spirometry improved a little in cohort 2 (74.2%) on cohort 1 (62.8%) but fell back for the COVID-era group (61.1%). In contrast, chest X-ray, FBC and BMI all improved after cohort 1 and were maintained for the COVID cohort; almost all patients received one of these. The proportion receiving all four before diagnosis jumped from 26.6% in cohort 1% to 46.7% in cohort 2 and was maintained in cohort 3 (43.0%). Modelling and funnel plots showed considerable non-random variation in spirometry use by practice, though with some improvement since cohort 1.

Conclusions: The recording of spirometry and chest X-rays warrants further and consistent improvement.