Reasons for the increasing Hispanic infant mortality rate: Florida, 2004-2007.

Assess whether the 55% increase in Florida's Hispanic infant mortality rate (HIMR) during 2004-2007 was real or artifactual. Using linked data from Florida resident live births and infant deaths for 2004-2007, we calculated traditional (infant Hispanic ethnicity from death certificates and maternal Hispanic ethnicity from birth certificates) and nontraditional (infant and maternal Hispanic ethnicity from birth certificate maternal ethnicity) HIMRs. We assessed trends in HIMRs (per 1,000 live births) using Chi-square statistics. We tested agreement in Hispanic ethnicity after implementation of a revised 2005 death certificate by using kappa statistics and used logistic regression to test the associations of infant mortality risk factors. Hispanic was defined as being of Mexican, Puerto Rican, Cuban, Central/South American, or other/unknown Hispanic origin. During 2004-2007 traditional HIMR increased 55%, from 4.0 to 6.2 (Chi-square, P < 0.001) and nontraditional HIMR increased 20%, from 4.5 to 5.4 (Chi-square, P = 0.03). During 2004-2005, agreement in Hispanic ethnicity did not change with use of the revised certificate (kappa = 0.70 in 2004; kappa = 0.76 in 2005). Birth weight was the most significant risk factor for trends in Hispanic infant mortality (OR = 1.33, 95% CI = 1.10-1.61). Differences in Hispanic reporting on revised death certificates likely accounted for the majority of traditional HIMR increase, indicating a primarily artifactual increase. Reasons for the 20% increase in nontraditional HIMR during 2004-2007 should be further explored through other individual and community factors. Use of nontraditional HIMRs, which use a consistent source of Hispanic classification, should be considered.