Is hypertension a more frequent risk factor for deep than for lobar supratentorial intracerebral haemorrhage?

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Abstract
To determine whether evidence from observational studies supports the widely held belief that hypertension is more commonly a risk factor for deep than for lobar supratentorial intracerebral haemorrhage. Studies comparing the frequency of hypertension as a risk factor for deep versus lobar supratentorial intracerebral haemorrhage, excluding haemorrhages with identified secondary causes, were identified and subjected to a meta-analysis. The effects of predefined methodological quality criteria on the results were assessed and other sources of bias were considered. The pooled result from all 28 included studies (about 4000 patients) found hypertension to be about twice as common in patients with deep as in those with lobar haemorrhage (odds ratio (OR) 2.10, 95% confidence interval (95% CI) 1.82 to 2.42), but there was significant heterogeneity between studies. The pooled OR was less extreme for studies that used a pre-stroke definition of hypertension, were population based or included first-ever strokes only. In the three studies meeting all criteria (601 patients), deep haemorrhage was associated with a smaller, statistically significant excess of hypertension (OR 1.50, 95% CI 1.09 to 2.07). The OR for studies confined to younger patients seemed to be more extreme (12.32, 95% CI 6.13 to 24.77), but none of these studies fulfilled our methodological quality criteria. Additional, unquantified sources of bias included uncertainty about whether those doctors reporting brain scans were blind to hypertension status, uncertain reliability of the classification of haemorrhage location and variable rates of investigation for secondary causes. An excess of hypertension was found in patients with deep versus lobar intracerebral haemorrhages without an identified secondary cause, but this may be due to residual, unquantified methodological biases.