Evaluating Pulmonary Function Change Over Time in the Occupational Setting

Abstract

Periodic spirometry testing is performed in medical screening and surveillance programs for workers with various occupational exposures and for cigarette smokers. The recent American College of Occupational and Environmental Medicine (ACOEM) evidence-based statement, Spirometry in the Occupational Setting, comprehensively reviewed the issues involved in conducting and interpreting standardized spirometry tests in occupational medicine. 1 However, interpreting change over time was only briefly discussed in that statement, and little other guidance on assessing longitudinal change in lung function is available for health professionals. As a result, many practitioners do not evaluate change in lung function over time, but instead repeatedly determine whether each year's test results fall within the normal range. Other practitioners evaluate change over time or "trending" but are unaware of the pitfalls that can distort their evaluations.Although health professionals must determine whether evaluating lung function change over time effectively screens for a specific outcome disease, 2-4 the ACOEM Occupational and Environmental Lung Disorder Committee recognized the need to provide guidance in the selection and use of simple measures of change over time. The Committee developed this separate ACOEM position statement to: 1) explain the need for longitudinal analysis of pulmonary function when evaluating employee respiratory health; 2) describe the pitfalls to be avoided when collecting serial measurements for longitudinal analysis; and 3) recommend simple criteria to use for flagging abnormal change in pulmonary function over time. The statement's key points are summarized in Table 1. Real-life examples illustrate the pitfalls to be avoided and the application of longitudinal methods for evaluating pulmonary function.

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