Regional differences in birth prevalence of congenital heart disease in Malta

Aim: Recent studies have shown a correlation between environmental pollutan ts and increased risk of selected congenital malformations. The South-East area of the Island of Malta is much more industrialised than the more rural North-West area. The aim of this study was to test the null hypothesis tha t there are no regional differences in Malta in the prevalence at birth of congenital cardiac malformations. Methods: Live born infants with congenita l cardiac malformations born between 1990 and 1994 were allocated to 10 are as, and thence to 2 regions of 5 areas each, so as to constitute North-West and South-East Malta. Official publications gave population totals and gro wth rates. Those infants with congenital cardiac malformations were then co mpared between the different regions using chi(2) and the Mann-Whitney U te st. Results: The overall prevalence of congenital heart disease at birth was 8. 8/1000 live births. The birth prevalence for the South-East region (10.1/10 00 LB - 95% CI 8.4-12.3/1000 live births) was significantly higher than for the North-West (7.4/1000 live births - 95% CI 6.0-9.0/1000 live births)- p =0.03, Odds ratio 1.38 (95% CI 1.05-1.80). The Mann-Whitney U test showed a significant difference in the distribution amongst the 10 defined areas (p =0.016). The Central-East area had the highest prevalence of cardiac malfor mations in the entire Island - p=0.02, Odds ratio 1.70 (95% CI 1.10-2.61). Demography showed an efflux of individuals from the South-East of Malta. Conclusion: The higher prevalence of congenital heart disease noted at birt h in South-East Malta is unlikely to be due to genetic factors, as these wo uld have migrated North-West along with the population movement. An environ mental factor, therefore, seems more likely to bet responsible For the incr eased predisposition to congenital heart disease in the South-East of Malta .