Development of the Lung Function Questionnaire (LFQ) to identify airflow obstruction

Area of Science:

• Pulmonary Medicine
• Diagnostic Tools
• Epidemiology

Background:

• Chronic obstructive pulmonary disease (COPD) diagnosis relies on spirometry.
• Early identification of patients needing spirometry is crucial for timely COPD management.
• A validated screening tool can improve diagnostic efficiency.

Purpose of the Study:

• To develop and refine the Lung Function Questionnaire (LFQ) for identifying patients requiring COPD diagnostic evaluation.
• To assess the accuracy and validity of the LFQ in detecting airflow obstruction.

Main Methods:

• Item selection and reduction using data from 387 adults aged 40+ with self-reported chronic bronchitis.
• Stepwise logistic regression for item reduction and receiver operating characteristic (ROC) analysis for accuracy assessment.
• Content and face validity evaluated through focus groups with physicians and interviews with COPD patients.

Main Results:

• A five-item model including age, smoking history, wheeze, dyspnea, and phlegm showed the highest classification accuracy (AUC = 0.720).
• Sensitivity was 73.2% and specificity was 58.2% for the five-item model.
• The criterion of three or more affirmative answers demonstrated the highest AUC for identifying airflow obstruction.

Conclusions:

• The five-item LFQ demonstrates adequate accuracy, sensitivity, and specificity for identifying individuals with potential COPD.
• The LFQ is a promising tool for preliminary screening and warrants further validation.
• The developed questionnaire aids clinicians in selecting appropriate patients for spirometry-based COPD evaluation.