Incidence and Mortality of Spontaneous Subarachnoid Hemorrhage in Martinique

Abstract

Background: Incidence of spontaneous subarachnoid hemorrhages (SAH) varies wildly across the world and seems to be low in Central and South America (4.2 per 100 000 person-years; CI 95%; 3.1-5.7). The objective of our study was to describe the characteristics of SAH and to estimate its incidence and severity in Martinique, a small French island located in the Caribbean Sea.

Methods: Due to its insular nature and small captive population, Martinique is ideal for the setting up of population-based epidemiological studies with good exhaustiveness. Our study, spanning a 7 year period (2007-2013), consisted of retrospective case ascertainment with multiple overlapping methods. Crude incidence and 30 day case-fatality rates for SAH among the Martinican population were computed for the study period. Incidence and disease severity was also analyzed according to age, gender and aneurysm presence. World age-standardized incidence rates were also calculated.

Results: A total of 121 patients had a SAH during the study period, with a higher frequency of female cases (71.1% versus 28.9%, p<0.001). Patient mean age was 57.1 years (median = 55 [46-66]). An aneurysmal origin was found in 96 SAH cases (79.3%). Crude annual incidence was 4.36 per 100 000 person-years (CI 95% 2.30-6.42). World age-standardized incidence was 3.29 per 100 000 person-years (CI 95% 1.74-4.84). During the 30 days following SAH diagnosis, 29 patients died (case fatality rate: 24% (CI 95% 16.4-31.6)).

Conclusions: The incidence of spontaneous subarachnoid hemorrhage in Martinique is much lower than in other parts of the world and similar to countries in Central and South America. These results are possibly related to environmental factors and most particularly to a low rate of smoking in the Martinican population. Thirty-day case-fatality rate is similar to what is observed in developed countries.

Fig 1. Number of spontaneous subarachnoid hemorrhages (SAH) recorded annually in Martinique between January 1st 2007 and December 31st 2013.

Fig 2. Distribution of aneurysm location, according to gender, on the circle of Willis in patients diagnosed with spontaneous subarachnoid hemorrhages (SAH) between January 1st 2007 and December 31st 2013 in Martinique.

Figure legend: ACa: Anterior communicating artery, ICa: Internal carotid artery, PCa: Posterior communicating artery, MCa: Middle cerebral artery, VBa: Verterbrobasilar arterial circulation, other: peri-callosal artery and 4 cases of SAH without vascular imaging exploration.

Fig 3. SAH incidence in Martinique compared to other regions.

Figure legend: Results are compared with the meta-analysis of de Rooij et al. [1]. All countries other than Japan, Finland and South and Central America (SCA) were pooled in a reference group (Reference countries). Number per 100 000 person-years, with corresponding 95% CI, are represented.