Carbon monoxide-related injury estimation using ICD-coded data: methodologic implications for public health surveillance.
Estimates of unintentional deaths from carbon monoxide (CO) poisoning can be obtained from national mortality data. We explored ways of accurately estimating CO-related deaths from International Classification of Diseases, 9th Revision (ICD-9) coded U.S. mortality data. We evaluated and identified CO-related ICD-9 codes and created five classes of codes for case ascertainment that represented a continuum of the degree of certainty that the ICD-coded death was truly CO-related. We conducted single (underlying) cause-of-death and multiple-cause-of-death analysis using 20 years of data (1979-1998), and calculated sensitivity and positive predictive value using different criteria for case ascertainment. Single-cause analysis provided accurate estimates only when we used CO-exclusive E-codes, however this method failed to identify approximately one third of the CO-related deaths over the study period. Single-cause analysis overestimated the number of CO-related deaths when we used E-codes that were not exclusive to CO exposure. Identification of true CO-related deaths required multiple cause-of-death analysis and use of the CO nature-of-injury code, N986, to confirm suspected cases. Sensitivity of N986 was 99.5%, and positive predictive value of the individual E-codes in single cause-of-death analysis ranged from 1.5% to 92%. Estimating CO-related deaths from ICD-coded data requires a thorough understanding of the ICD codes, coding rules, and of the limitations imposed by case selection criteria and single cause-of-death analysis.
Ball
Lauren B
LB
Indoor Air Solutions, Tallahassee, FL 32303, USA. LBALLIAQ@mindspring.com
Macdonald
Steven C
SC
Mott
Joshua A
JA
Etzel
Ruth A
RA
D000393:Air Pollutants / Q000506:poisoning*; D002249:Carbon Monoxide Poisoning / Q000401:mortality*; D002423:Cause of Death; D006801:Humans; D038801:International Classification of Diseases; D011159:Population Surveillance / Q000379:methods*; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology
D000393:Air Pollutants