Ayesha Sajjad

Reliable quantification of the burden of stroke in low- and middle-income (LMI) countries is difficult as population-based surveillance reports are scarce and may vary considerably in methodology. We aimed to evaluate all available primary stroke surveillance studies by applying components of a benchmark protocol (WHO STEPwise approach to stroke surveillance) and quantify the reported burden of stroke in LMI settings. Electronic databases Medline, Embase, Scopus, and Web of Knowledge were searched for population-based surveillance studies. Studies conducted in the LMI countries that reported on incident stroke were included. Data were extracted from each study using a prestructured format. Information on epidemiologic measures including crude and age-adjusted incidence rates, person-years, admission rates, case fatality rates, death certification, autopsy rates, measures of disability, and other study-specific information, in line with WHO STEPS stroke protocol, were recorded. Age-adjusted incidence rate data of stroke were combined using random-effects meta-analyses. We identified 7 studies that reported on burden of stroke in 9 LMI countries, including aggregate information from 1,711,372 participants collected over 5,240,923 person-years. The age-adjusted incidence rates across the LMI countries varied widely, with the burden of total first-ever strokes ranging from 41 to 909 events per 100,000 person-years. Systematic evaluation of all available primary surveillance studies, particularly in the context of WHO STEPS guidelines, indicates inadequate adherence to standardized surveillance methodology in LMI countries. Incorporation of standardized approaches is essential to enhance generalizability and estimate stroke burden accurately in these resource-poor settings.

Breastfeeding has been related to better cognitive development in children. However, due to methodological challenges, such as confounding, recall bias or insufficient power, the mechanism and nature of the relation remains subject to debate. We included 3761 participants of a population-based cohort study from fetal life onwards and examined the association of breastfeeding duration with non-verbal intelligence in children of age 6 years. Maternal and paternal lifestyle, sociodemographic factors, child factors and maternal IQ were tested for their confounding effects on the association. We observed an initial association between breastfeeding duration and child IQ conferring an advantage of 0.32 (0.20 to 0.44) points for each additional month of breastfeeding. This association strongly attenuated to 0.09 (-0.03 to 0.21) points after adjustment for child factors, sociodemographic factors, parental lifestyle factors and maternal IQ. Similarly, the associations with breastfeeding dura...

Available literature suggests that both vitamin D and calcium may be associated with a wide range of non-skeletal outcomes. However, epidemiological evidence supporting their individual associations with incident cerebrovascular disease is scarce. We conducted a systematic review and meta-analysis of prospective cohort studies, published before February 2012 and sought from MEDLINE, EMBASE, BIOSIS and the Science Citation Index databases, and reported cerebrovascular disease (defined as any fatal or non-fatal ischemic stroke, hemorrhagic stroke, cerebrovascular accident or transient ischemic attack) by circulating vitamin D (25-hydroxy vitamin D [25(OH)D] as active metabolite) and calcium levels. Two independent investigators abstracted information on 25(OH)D and calcium, cerebrovascular outcomes and other characteristics from selected studies. Relative risks (RRs) were pooled by both random and fixed effects meta-analyses and were further examined under different study-level characteristics. Publication bias was assessed with funnel plots and Egger's asymmetry test. From 5,778 initial references, nine unique prospective cohort studies met our inclusion criteria. Seven studies (involving 47,809 participants and 926 cerebrovascular events) focused on circulating 25(OH)D and 3 reported on circulating calcium (22,577 participants and 727 events). For 25(OH)D, in a comparison of individuals in the top third versus those in the bottom third at baseline, the combined RR for cerebrovascular disease, adjusted for several conventional risk factors, was 0.60 (95 % CI 0.48, 0.72). The corresponding RR in the prospective studies that reported on baseline circulating calcium levels for cerebrovascular disease was 1.40 (95 % CI 1.19, 1.64). There was no apparent evidence of heterogeneity or publication bias among included studies. Available data indicate that higher circulating level of vitamin D is associated with a decreased risk of cerebrovascular disease. Conversely, higher circulating calcium concentration is associated with an increased risk of cerebrovascular disease.