An algorithm for the surveillance of occupational chronic obstructive pulmonary disease in Washington state

An estimated 14% of chronic obstructive pulmonary disease (COPD) is caused by occupational exposure to vapor, gas, dust, and fumes (VGDF).

In collaboration with the Washington State Department of Labor and Industries' Safety and Health Assessment and Research for Prevention Program, we developed a surveillance algorithm for retrospective identification of occupational COPD using a cohort of Washington workers.

Potential cases were identified from workers' compensation claims filed in Washington State between 2010 and 2020 using keywords, disease diagnosis codes, and occupational injury and illness codes. Cases were confirmed for the presence of COPD using postbronchodilator forced expiratory volume over 1-second/forced vital capacity (FEV1/FVC) ratio <0.7. If spirometry was unavailable, alternate clinical criteria were used. In an iterative process based on review of the first 100 cases and longitudinal studies on occupational COPD, we developed an algorithm to classify cases as probable, possible, work-aggravated, or unlikely occupational COPD. This algorithm incorporated confirmation of COPD diagnosis, total career duration with exposure to medium or high VGDF, and smoking history. Exposure risk was estimated using a COPD-specific, occupation-based job exposure matrix.

Of 508 potential cases identified in the workers' compensation claims data, 494 had a COPD diagnosis and were included in the final analysis. Of these, 132 (27%) met criteria for occupational COPD, including 72 probable, 4 possible, and 56 work-aggravated cases. There were 362 (73%) cases that did not meet criteria and were classified as unlikely to have occupational COPD. Overall, 19 cases with occupational COPD were among people who had never smoked or had smoked <10 pack-years total, including 17 classified as probable and 2 classified as work-aggravated. Occupations ascribed through the job exposure matrix to have medium or high exposure to VGDF included construction workers, production workers, maintenance workers, and drivers, among others, and there was overlap in occupations and hazards between occupational COPD classifications.

This comprehensive algorithm provides an approach for occupational COPD surveillance that can be used to inform and prioritize prevention efforts in an effort to reduce disease burden in high-risk occupations.