International Classification of Diseases Clinical Modification: An Application to the Occupational Health Indicators

BACKGROUND:  Occupational health indicators are used by state health agencies as a measure of the health status with respect to workplace injuries and illnesses within their state. Two indicators use hospital discharge data to calculate the number of hospitalizations for work-related burns, and from or with pneumoconiosis using assigned diagnoses codes. These codes are based on the World Health Organization's International Classification of Diseases (ICD) Clinical Modification (CM), 9^th Revision (ICD-9-CM). By 2014, the new ICD-CM 10^th Revision (ICD-10-CM) will be implemented. There is a need to evaluate the impact of this transition on the calculation of these two occupational health indicators.

METHODS:  An on-line medical coding tool was used to convert the diagnoses codes used to identify hospitalizations for work-related burns, and from or with pneumoconiosis from ICD-9-CM to ICD-10-CM. For each condition, a crosswalk table was created. Using this table, the text describing each code set was compared to evaluate whether a one-to-one match exist between revisions. The 1990–2009 National Hospital Discharge Survey (NHDS) unweighted data were used to determine the range of ICD-9-CM codes for each indicator, and to evaluate whether all ICD-9-CM coded cases would be captured with corresponding ICD-10-CM codes.

RESULTS:   For every ICD-9-CM code for burns there is a corresponding ICD-10-CM code and vice versa suggesting that no cases will be lost or gained using the corresponding ICD-10-CM codes. The assigned ICD-10-CM code depends on whether the injury is a burn or corrosion of the body part. The codes used for pneumoconiosis are a one-to-one match between ICD-9-CM and ICD-10-CM, except for unspecified pneumoconiosis. In ICD-10-CM, one additional condition (pneumoconiosis associated with tuberculosis, code J65) converts back to unspecified pneumoconiosis in ICD-9-CM suggesting additional cases may be gained if J65 is included. Using twenty years of NHDS unweighted data suggested very little impact on the hospitalization calculations for work-related burns, and discharges from or with pneumoconiosis using the ICD-10-CM.

CONCLUSIONS:   These results suggest that using the new set of codes will have little impact on the hospitalization calculations for work-related burns, and discharges from or with pneumoconiosis. These results provide assurance to state health agencies that most cases will be captured when implementing the ICD-10-CM codes on the hospitalization discharge data for these two indicators.