Winter Excess in Hospital Admissions, In-Patient Mortality and Length of Acute Hospital Stay in Stroke: A Hospital Database Study over Six Seasonal Years in Norfolk, UK

Abstract

Background: Several studies have examined the incidence and mortality of stroke in relation to season. However, the evidence is conflicting partly due to variation in the populations (community vs. hospital-based), and in climatic conditions between studies. Moreover, they may not have been able to take into account the age, sex and stroke type of the study population. We hypothesized that the age, sex and type of stroke are major determinants of the presence or absence of winter excess in morbidity and mortality associated with stroke. Methods: We analyzed a hospital-based stroke register from Norfolk, UK to examine our prior hypothesis. Using Curwen’s method, we performed stratified sex-specific analyses by (1) seasonal year and (2) quartiles of patients’ age and stroke subtype and calculated the winter excess for the number of admissions, in-patient deaths and length of acute hospital stay. Results: There were 5,481 patients (men = 45%). Their ages ranged from 17 to 105 years (median = 78 years). There appeared to be winter excess in hospital admissions, deaths and length of acute hospital stay overall accounting for 3/100,000 extra admissions (winter excess index of 3.4% in men and 7.6% in women) and 1/100,000 deaths (winter excess index of 4.7 and 8.6% in women) due to stroke in winter compared to non-winter periods. Older patients with non-haemorrhagic stroke mainly contribute to this excess. If our findings are replicated throughout England and Wales, it is estimated that there are 1,700 excess admissions, 600 excess in-patient deaths and 24,500 extra acute hospital bed days each winter, related to stroke within the current population of approximately 60 million. Conclusions: Further research should be focused on the determinants of winter excess in morbidity and mortality associated with stroke. This may subsequently reduce the morbidity and mortality by providing effective preventive strategies in future.

Prior antiplatelet therapy and outcome following intracerebral hemorrhage

“…4 Two cohorts excluded patients admitted later than 24 hours after symptom onset, 21,23 2 excluded patients with prior stroke, 5,26 1 excluded patients "diagnosed with amyloid angiopathy," 20 and 1 excluded patients with multiple ICH, prior ICH, pre-ICH disability, or need for surgery. 30 We contacted study authors to request cohort data excluding patients taking anticoagulation and ultimately received data from 23 cohorts that specifically excluded patients on anticoagulation, [1][2][3][4][5]8,9,11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] while one cohort included patients on anticoagulation, 10 and one cohort included patients on anticoagulation but controlled for its use in the multivariable model of mortality. 12 There was no evidence of publication bias in the 10 previously published studies ( p ϭ 0.34 for mortality and p ϭ 0.54 for poor outcome, by Egger's test) or when considering all 25 studies ( p ϭ 0.24 for mortality and p ϭ 0.49 for poor outcome) (figure 1).…”

“…Data from an additional 15 cohorts were obtained by these methods. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In many cases, authors contributed more patients than described in the original cohort, which was allowed as long as these patients were collected and characterized according to the same published methods. Study quality was evaluated using the same criteria cited above.…”

Seasonal variation in plasma free normetanephrine concentrations: implications for biochemical diagnosis of pheochromocytoma

“…Such influences have also been reported to be associated with seasonal variations in blood pressure (4,5,6), possibly contributing to excess cardiovascular morbidity and mortality in winter than in summer (7,8,9,10,11,12,13,14). Although seasonal variations in plasma concentrations of catecholamines are well established, it is not clear whether this influences plasma concentrations of normetanephrine and metanephrine, the respective O-methylated metabolites of norepinephrine and epinephrine, now used increasingly for the diagnosis of pheochromocytoma (15).…”

Are Stroke Occurrence and Outcome Related to Weather Parameters? Results from a Population-Based Study in Northern Portugal

“…Deaths from acute myocardial and cerebral infarction contribute to the excess winter mortality [2][3][4] , but routine mortality statistics may over-report the number of stroke deaths [5,6] confounded by poststroke complications. On the other hand, the incidence of stroke in most countries has a seasonal pattern, peaking during winter [7][8][9] , with a lesser frequency in spring [10,11] , autumn [12] or summer months [13] . These seasonal/ monthly effects are important to adopt preventive measures and to estimate the overall hospital and/or stroke units' workload, but fell short of demonstrating meteorological factors underlying and triggering stroke occurrence, in particular a first-in-a-lifetime stroke.…”