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.