Development of the Birmingham Lung Improvement Studies (BLISS) prognostic score for COPD patients in primary care: data from the Birmingham COPD cohort

Conference:

2020 SW SAPC Bristol

Talk Code:

1D.3

Presenter:

Andrew P Dickens

Twitter:

@ap_dickens

Co-authors:

Rachel E Jordan1, David Fitzmaurice2, James Martin1, Alice Sitch1, Jon G Ayres1 , KK Cheng1, Brendan G Cooper3, Amanda Daley4, Alexandra Enocson1, Sheila Greenfield1, Kate Jolly1, Sue Jowett1, Martin R Miller1, Richard D Riley5, Stanley Siebert6, Robert A Stockley3, Alice M Turner1, Peymané Adab1

Author institutions:

1. Institute of Applied Health Research, University of Birmingham; 2. Clinical Trials Unit, University of Warwick; 3. Lung Function and Sleep Investigational Unit, University Hospitals Birmingham; 4. School of Sport Exercise and Health Sciences, University of Loughborough; 5. Centre for Prognosis Research, Keele University; 6. Business School, University of Birmingham

Problem

COPD patients in primary care have high rates of hospital admissions. Prognostic scores could be used to guide management of COPD patients and reduce risk of hospital admission, but existing scores do not perform well enough and are not used in practice. We aimed to develop a new prognostic score that was practical for use in the primary care setting.

Approach

Using data from the Birmingham COPD cohort we developed and internally validated the new BLISS prognostic score to predict respiratory admissions in 2-years from 23 candidate predictors. 1558 patients on COPD registers of 71 GP practices and 331 newly-identified patients from a linked case-finding trial were included and their self-reported and clinical data were combined with routine hospital episode statistics. The primary outcome was the record of at least one respiratory admission within 2 years of cohort entry (May 2012-June 2014). The model was developed using backward elimination of variables with p<0.157. Missing data were imputed using chained equations. Discrimination and calibration were assessed. Bootstrapping was used for internal validation, adjusting for overfitting and deriving optimum-adjusted performance statistics.

Findings

Median (min, max) follow up was 3.0 years (1.8, 3.8). Of the 23 candidate predictors, 6 variables were retained in the final model: age, CAT score, respiratory admissions in the previous 12m, BMI, diabetes, FEV1% predicted. After adjustment for optimism, the model showed promising discrimination in predicting risk of respiratory admissions by 2 years (c-statistic=0.73 (95%CI 0.70, 0.77). The BLISS score showed promising performance in predicting respiratory admissions compared with existing published scores.

Consequences

All 6 variables are readily available in primary care records or would be easy to collect, and a simple computer programme could calculate the score. Important next steps are external validation in other settings, proposing and evaluating a model of use to guide patient management and exploration of the best ways to implement the score in primary care practice.

Submitted by:

Andy Dickens

Funding acknowledgement:

This abstract presents independent research funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme ((Grant Reference Number RP-PG-0109-10061). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. The Birmingham COPD Cohort study is part of The Birmingham Lung Improvement StudieS – BLISS.