Seasonal hypertension: A clue to explain the high prevalence of unrecognized hypertension in the elderly? Gruppo Italiano di Farmacovigilanza nell'Anziano (GIFA)

Background and aims: Blood pressure is known to be influenced by the season, particularly in the elderly. The association between cold weather and unrecognized hypertension has not been previously studied. The present study aimed at assessing whether recognition of hypertension in the elderly follows a seasonal pattern. Methods: All patients over 64 with either first-listed or secondary diagnosis of hypertension at discharge (N=4487) out of 24585 consecutively admitted to 69 wards of Geriatrics or Internal Medicine during ten bi-monthly observation periods (May-June and September-October) were enrolled. The main outcome of the study was the prevalence of unrecognized hypertension, defined as no mention of hypertension and/or antihypertensive drugs in clinical histories collected on admission, and a first-listed or secondary discharge diagnosis of hypertension. Results: We found a total of 928 patients with unrecognized hypertension. Being admitted in the September-October period was independently associated with the outcome unrecognized hypertension (OR 1.25, 95% CI 1.08-1.46), as were smoking addiction (OR 1.57, 95% CI 1.23-2.0) and allocation to a medical word (OR 1.21, 95% CI 1.04-1.41). Negative correlates of the outcome were multiple pathologies (OR 0.85, 95% CI 0. 73-0.99), discharge diagnosis of coronary artery disease (OR 0.77, 95 % CI 0.64-0.92) or diabetes mellitus (OR 0.81, 95% CI 0.67-0.97). Conclusions: Hypertension in the elderly may at least partly follow a seasonal pattern, and this finding may be relevant for screening and therapeutic decisions.