Chronic Obstructive Pulmonary Disease in primary care; from case finding to improving patient outcomes: the Birmingham Lung Improvement Studies (BLISS) research programme

Research output: Contribution to journalArticle

Colleges, School and Institutes

External organisations

  • Department of Lung Function and Sleep.
  • Research Institute of Primary Care and Health Sciences
  • Keele University
  • UNIVERSITY HOSPITAL BIRMINGHAM NHS FOUNDATION TRUST
  • University Hospitals Birmingham NHS Trust

Abstract

Chronic obstructive pulmonary disease (COPD) is a major contributor to morbidity, mortality and health service costs, but is vastly underdiagnosed. Evidence on screening and how best to approach this is not clear. There are also uncertainties around the natural history (prognosis) of COPD and how it impacts on work performance.

Objectives:
WP1: To evaluate alternative methods for screening for undiagnosed COPD in primary care, with effectiveness and cost-effectiveness analyses and an economic model of a routine screening programme
WP2: To recruit a primary care COPD cohort, develop a prognostic model (BLISS) to predict risk of respiratory hospital admissions, validate an existing model to predict mortality risk, address some uncertainties about natural history, and explore the potential for a home exercise intervention.
WP3: To identify which factors are associated with employment, absenteeism, presenteeism (poor performance in work) and evaluate the feasibility of offering formal occupational health (OH) assessment to improve work performance

Design:
WP1: Cluster randomised controlled trial with household-level randomised comparison of two alternative case-finding approaches, in the intervention arm
WP2: Cohort study; focus groups (FG)
WP3: Sub-cohort; feasibility study

Setting: Primary care settings in West Midlands, UK.

Participants:
WP1: 74,818 ever-smokers aged 40–79 years without a previous COPD diagnosis from 54 general practices.
WP2: 741 patients with previously diagnosed COPD (71 practices) and participants from WP1 RCT. 26 took part in FG.
WP3: Occupational sub-cohort with 248 patients in paid employment at baseline. 35 took part in occupational health intervention feasibility study.

Interventions/exposures:
WP1: Targeted case-finding: symptom screening questionnaire, r administered opportunistically or additionallyby post, followed by diagnostic post-bronchodilator spirometry. Comparator: routine care.
WP2: 23 candidate variables selected from literature and expert review
WP3: Sociodemographic, clinical and occupational characteristics; OH assessment and recommendations

Main outcome measures:
WP1: yield (screen-detected COPD) and cost-effectiveness of case-finding; effectiveness of screening on respiratory hospitalisation and mortality after ~4 years.
WP2: respiratory hospitalisation within 2-years; barriers and facilitators to physical activity
WP3: work performance; feasibility and acceptability of the OH intervention and study processes.

Results:
WP1: Targeted case-finding resulted in greater yield of previously undiagnosed COPD than routine care at 1-year (n=1278 (4%) vs n=337 (1%); adjusted odds ratio [OR] 7.45 [95%CI 4.80, 11.55]), and a model based estimate of a regular screening programme suggested an incremental cost-effectiveness ratio of £16,596 per additional QALY gained. However, long-term follow-up of the trial showed that at ~4-years, there was no clear evidence that case-finding, compared to routine practice, was effective in reducing respiratory admissions (adjusted hazard ratio [HR] 1.04; 95%CI: 0.73, 1.47) or mortality (HR 1.15; 95%CI 0.82, 1.61).
WP2: 2,305 patients, including 1,564 with previously diagnosed COPD and 741 WP1 participants (330 with, 411 without obstruction) were recruited. The BLISS prognostic model among cohort participants with confirmed airflow obstruction (n=1894) included 6 of 23 candidate variables (age, COPD Assessment Test score, 12-month respiratory admissions, BMI, diabetes, FEV1% predicted). After internal validation and adjustment (uniform shrinkage factor 0.87, 95%CI: 0.72, 1.02), the model discriminated well in predicting 2-year respiratory hospital admissions (c-statistic =0.75 (95%CI 0.72, 0.79).
In FG, physical activity engagement was related to self-efficacy and symptom severity.
WP3: In the occupational sub-cohort, increasing dyspnoea and exposure to inhaled irritants were associated with lower work productivity at baseline. Longitudinally, increasing exacerbations and worsening symptoms, but not a decline in airflow obstruction, were associated with absenteeism and presenteeism. The acceptability of the occupational health intervention was low leading to low uptake and low implementation of recommendations, making a full trial unfeasible.

Limitations:
WP1: Even with the most intensive approach, only 38% responded to the case-finding invitation. Management of case-found patients with COPD in primary care was generally poor, limiting interpretation of the long-term effectiveness of case-finding on clinical outcomes.
WP2: The components of the BLISS model may not always be routinely available and calculation of the score requires a computerised system.
WP3: Relatively few cohort participants were in paid employment at baseline, limiting the interpretation of predictors of lower work productivity.

Conclusions: This programme has addressed some of the major uncertainties around screening for undiagnosed COPD, resulted in the development of a novel, accurate model for predicting respiratory hospitalisation in people with COPD, and the inception of a primary care COPD cohort for longer term follow-up. We have also identified factors that may affect work productivity in people with COPD, as potential targets for future intervention.

Future work: We plan to obtain data for longer-term follow up of trial participants at 10-years. The BLISS model needs to be externally validated. Our primary care COPD cohort is a unique resource for addressing further questions to better understand the prognosis of COPD.

Details

Original languageEnglish
JournalERO
Publication statusAccepted/In press - 14 Feb 2020

Keywords

  • COPD, case-finding, screening, primary health care, cluster RCT, effectiveness, cost-effectiveness, cohort studies, prognosis, presenteeism, absenteeism, occupational health, work performance