Monitoring maternal mortality using vital records linkage.

We developed a method to identify maternal deaths (deaths to women within 365 days of delivery) by linking Tennessee vital records. A computerized algorithm compared personal identifiers from the death certificates of reproductive-aged women to maternal identifiers on birth and fetal death certificates. For each decedent record which met the study criteria, the algorithm calculated a "match score" by comparing common elements in both files. The algorithm awarded full credit for data elements that agree exactly, partial credit for elements in partial agreement, and subtracted credit for information that mismatched. Match scores ranged from 0 to 35 for the 9,009 deaths in women 10-55 years of age during the three study years, with the majority of scores (96.3%) being 0 for "no match." Match scores of 1 to 8 were obtained by 153 (1.7%) of decedent records, while scores greater than 9 were obtained by 184 (2.0%) of decedent records. We used nurse-abstracted hospital, autopsy, and coroner records as our standard to verify the linkages. Manual review of personal identifiers showed that scores of 12 or less were not a match while scores of 13 or more indicated "true" matches. Based on this cutoff, the linkage algorithm yielded 130 maternal deaths. Of these, 32 (25%) were classified as truly pregnancy-related upon medical record review by an obstetrician. The remaining 98 deaths were associated only temporally with pregnancy. During the same time period, 16 individuals were identified to the State Health Department on their death certificates as dying from pregnancy-related causes, including one not identified by the linkage process.(ABSTRACT TRUNCATED AT 250 WORDS)