Discriminative Accuracy of the CAPTURE Tool for Identifying Chronic Obstructive Pulmonary Disease in US Primary Care Settings

Abstract

Importance: Chronic obstructive pulmonary disease (COPD) is underdiagnosed in primary care.

Objective: To evaluate the operating characteristics of the CAPTURE (COPD Assessment in Primary Care To Identify Undiagnosed Respiratory Disease and Exacerbation Risk) screening tool for identifying US primary care patients with undiagnosed, clinically significant COPD.

Design, setting, and participants: In this cross-sectional study, 4679 primary care patients aged 45 years to 80 years without a prior COPD diagnosis were enrolled by 7 primary care practice-based research networks across the US between October 12, 2018, and April 1, 2022. The CAPTURE questionnaire responses, peak expiratory flow rate, COPD Assessment Test scores, history of acute respiratory illnesses, demographics, and spirometry results were collected.

Exposure: Undiagnosed COPD.

Main outcomes and measures: The primary outcome was the CAPTURE tool's sensitivity and specificity for identifying patients with undiagnosed, clinically significant COPD. The secondary outcomes included the analyses of varying thresholds for defining a positive screening result for clinically significant COPD. A positive screening result was defined as (1) a CAPTURE questionnaire score of 5 or 6 or (2) a questionnaire score of 2, 3, or 4 together with a peak expiratory flow rate of less than 250 L/min for females or less than 350 L/min for males. Clinically significant COPD was defined as spirometry-defined COPD (postbronchodilator ratio of forced expiratory volume in the first second of expiration [FEV1] to forced vital capacity [FEV1:FVC] <0.70 or prebronchodilator FEV1:FVC <0.65 if postbronchodilator spirometry was not completed) combined with either an FEV1 less than 60% of the predicted value or a self-reported history of an acute respiratory illness within the past 12 months.

Results: Of the 4325 patients who had adequate data for analysis (63.0% were women; the mean age was 61.6 years [SD, 9.1 years]), 44.6% had ever smoked cigarettes, 18.3% reported a prior asthma diagnosis or use of inhaled respiratory medications, 13.2% currently smoked cigarettes, and 10.0% reported at least 1 cardiovascular comorbidity. Among the 110 patients (2.5% of 4325) with undiagnosed, clinically significant COPD, 53 had a positive screening result with a sensitivity of 48.2% (95% CI, 38.6%-57.9%) and a specificity of 88.6% (95% CI, 87.6%-89.6%). The area under the receiver operating curve for varying positive screening thresholds was 0.81 (95% CI, 0.77-0.85).

Conclusions and relevance: Within this US primary care population, the CAPTURE screening tool had a low sensitivity but a high specificity for identifying clinically significant COPD defined by presence of airflow obstruction that is of moderate severity or accompanied by a history of acute respiratory illness. Further research is needed to optimize performance of the screening tool and to understand whether its use affects clinical outcomes.

Figure 1.. Cohort Development and Participant Classification in the CAPTURE Trial

The number of patients approached for enrollment was not available because these data were not collected at all study sites. Not all patients approached were eligible because screening included queries related to self-reported prior chronic obstructive pulmonary disease (COPD) diagnosis, recent myocardial infarction, recent respiratory infection treated with antibiotics, and cataract surgery. CAPTURE indicates COPD Assessment in Primary Care To Identify Undiagnosed Respiratory Disease and Exacerbation Risk; FEV₁, forced expiratory volume in the first second of expiration; FVC, forced vital capacity. ^aAt analysis time, it was found that FEV₁ prediction inputs (sex, race, age, and height) recorded during spirometry sometimes disagreed with the values recorded separately in the study forms, and the correct values could not be verified. Patients with a resulting discrepancy of greater than 5% in the FEV₁ predicted value were excluded from the analysis.

Figure 2.. Receiver Operating Characteristic Curve for Detecting Clinically Significant Chronic Obstructive Pulmonary Disease (COPD) Under Alternative Definitions of a Positive Screening Result

The curve was obtained by shifting the COPD Assessment in Primary Care To Identify Undiagnosed Respiratory Disease and Exacerbation Risk (CAPTURE) questionnaire score thresholds that determine who is positive or negative for clinically significant COPD based on the questionnaire alone, and who requires peak expiratory flow rate (PEFR) to determine positivity. The PEFR thresholds of 350 L/min for males and 250 L/min for females were used throughout. Three of the points on the curve are labeled to illustrate how the criteria for CAPTURE positivity shift along the curve. Sensitivity indicates the probability of meeting defined screen-positive criteria in those with clinically significant COPD. Specificity indicates the probability of not meeting defined screen-positive criteria in those without clinically significant COPD.

Figure 3.. Spirometry- and Symptom-Based Classification of Patients With a Positive or Negative Screening Result for Detecting Clinically Significant Chronic Obstructive Pulmonary Disease (COPD)

COPD was defined a postbronchodilator ratio of forced expiratory volume in the first second of expiration to forced vital capacity (FEV₁:FVC) less than 0.70 or a prebronchodilator FEV₁:FVC less than 0.65 in patients who did not complete postbronchodilator spirometry, and was considered clinically significant if the patient also had either 1 or more acute respiratory illnesses within the past 12 months or an FEV₁ less than 60% of the predicted value. Clinically significant COPD was measured using spirometry with an FEV₁ less than 60% of the predicted value or a history of acute respiratory illness within the past 12 months. A preserved ratio impaired spirometry result indicates no spirometry-defined COPD and an FEV₁ less than 80% of the predicted value. A normal spirometry result indicates no spirometry-defined COPD or a preserved ratio impaired spirometry result. CAT indicates COPD Assessment Test.