Descriptive review of asbestosis and silicosis hospitalization trends in North Carolina, 2002-2011

Asbestosis and silicosis are debilitating pulmonary conditions resulting from inhalation of asbestos fibers or silica dust.

We provide a descriptive analysis of asbestosis and silicosis hospitalizations in North Carolina to assess trends over a 10-year period.

Events were defined as inpatient hospital discharges during the period 2002-2011 with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code of 501 or 502. Using statewide discharge data for 2002-2011, we calculated asbestosis and silicosis hospitalization rates in North Carolina (by demographics, hospital length of stay, cost, and payment type) and compared them with national rates.

In North Carolina, average annual age-standardized hospitalization rates for asbestosis and silicosis were 71.2 hospitalizations per 1 million residents and 6.2 hospitalizations per 1 million residents, respectively. Rates for asbestosis and silicosis decreased significantly (less than .01 for both conditions) between 2002 and 2011, by 46% and 67%, respectively. Men had significantly higher rates than women (less than .01), more than half of hospitalizations were among persons aged 65-84 years, and Medicare was the predominant payment source. The highest silicosis rates by county were clustered in Western North Carolina; no geographic patterns were observed for asbestosis. The estimated average annual cost statewide for these hospitalizations was $10,170,417 for asbestosis and $886,143 for silicosis.

ICD-9-CM misclassification and duplicate hospitalization records may have biased the observed rates of asbestosis and silicosis.

Decreases in hospitalization rates in North Carolina may be due to misdiagnosis, underreporting, or the declining use of asbestos in industries. Obtaining complete exposure histories at diagnosis is useful for continued public health surveillance.