The Latin American network for congenital malformation surveillance: ReLAMC.

The early detection of congenital anomaly epidemics occurs when comparing current with previous frequencies in the same population. The success of epidemiologic surveillance depends on numerous factors, including the accuracy of the rates available in the base period, wide population coverage, and short periodicity of analysis. This study aims to describe the Latin American network of congenital malformation surveillance: ReLAMC, created to increase epidemiologic surveillance in Latin America. We describe the main steps, tasks, strategies used, and preliminary results. From 2017 to 2019, five national registries (Argentina [RENAC], Brazil [SINASC/SIM-BRS], Chile [RENACH], Costa Rica [CREC], Paraguay [RENADECOPY-PNPDC]), six regional registries (Bogotá [PVSDC-Bogota], Cali [PVSDC-Cali], Maule [RRMC SSM], Nicaragua [SVDC], Nuevo-León [ReDeCon HU], São Paulo [SINASC/SIM-MSP]) and the ECLAMC hospital network sent data to ReLAMC on a total population of 9,152,674 births, with a total of 101,749 malformed newborns (1.1%; 95% CI 1.10-1.12). Of the 9,000,651 births in countries covering both live and stillbirths, 88,881 were stillborn (0.99%; 95% CI 0.98-0.99), and among stillborns, 6,755 were malformed (7.61%; 95% CI 7.44-7.79). The microcephaly rate was 2.45 per 10,000 births (95% CI 2.35-2.55), hydrocephaly 3.03 (2.92-3.14), spina bifida 2.89 (2.78-3.00), congenital heart defects 15.53 (15.27-15.79), cleft lip 2.02 (1.93-2.11), cleft palate and lip 2.77 (2.66-2.88), talipes 2.56 (2.46-2.67), conjoined twins 0.16 (0.14-0.19), and Down syndrome 5.33 (5.18-5.48). Each congenital anomaly showed heterogeneity in prevalence rates among registries. The harmonization of data in relation to operational differences between registries is the next step in developing the common ReLAMC database.

How valid are the rates of Down syndrome internationally? Findings from the International Clearinghouse for Birth Defects Surveillance and Research.

Rates of Down syndrome (DS) show considerable international variation, but a systematic assessment of this variation is lacking. The goal of this study was to develop and test a method to assess the validity of DS rates in surveillance programs, as an indicator of quality of ascertainment. The proposed method compares the observed number of cases with DS (livebirths plus elective pregnancy terminations, adjusted for spontaneous fetal losses that would have occurred if the pregnancy had been allowed to continue) in each single year of maternal age, with the expected number of cases based on the best-published data on rates by year of maternal age. To test this method we used data from birth years 2000 to 2005 from 32 surveillance programs of the International Clearinghouse for Birth Defects Surveillance and Research. We computed the adjusted observed versus expected ratio (aOE) of DS birth prevalence among women 25-44 years old. The aOE ratio was close to unity in 13 programs (the 95% confidence interval included 1), above 1 in 2 programs and below 1 in 18 programs (P < 0.05). These findings suggest that DS rates internationally can be evaluated simply and systematically, and underscores how adjusting for spontaneous fetal loss is crucial and feasible. The aOE ratio can help better interpret and compare the reported rates, measure the degree of under- or over-registration, and promote quality improvement in surveillance programs that will ultimately provide better data for research, service planning, and public health programs.