Evaluation of prenatal care information on birth certificates.
Misclassification frequently leads to bias in epidemiological studies, and causes concern for perinatal epidemiologists interested in using birth certificates as a data source. We used a maximum likelihood method to estimate the classification probabilities (conditional probabilities that indicate the probability of classification in a particular category, given the person's true category) of two data sources for a three-category outcome of prenatal care. The probability that women receiving adequate or inadequate care were correctly classified was estimated to be greater than 90%. The probability was much lower (< 35%) that women receiving intermediate care were correctly classified. The misclassification women from the intermediate category resulted in poor predictive values (< 70%) of women classified as receiving either adequate or inadequate care. Because of these findings, we combined the adequate and intermediate categories to form a two-category classification system. This revision resulted in higher positive predictive values (> 90%) with only a slightly lower classification probability (> 85%) for the combined category. We conclude that the degree of accuracy for a two-category classification of prenatal care based upon birth certificate information is acceptable, but we question the accuracy of indices of prenatal care with more than two categories.
McDermott
J
J
Department of Epidemiology, Rollins School of Public Health of Emory University, Atlanta, USA.
Drews
C
C
Green
D
D
Berg
C
C
D001719:Birth Certificates; D016022:Case-Control Studies; D005260:Female; D005845:Georgia / Q000453:epidemiology; D005865:Gestational Age; D006302:Health Services Research / Q000706:statistics & numerical data*; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D016013:Likelihood Functions; D011247:Pregnancy; D011295:Prenatal Care / Q000145:classification / Q000706:statistics & numerical data*; D011785:Quality Assurance, Health Care; D012042:Registries / Q000592:standards*; D015203:Reproducibility of Results; D012959:Socioeconomic Factors