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Who's at risk and why?

Adults :: Excess winter deaths :: Who's at risk and why?

Many studies demonstrate links between winter mortality and climate, even quantifying the increase in mortality per degree drop in temperature, yet outdoor temperature alone cannot explain all excess winter mortality (EWM). The Eurowinter study showed that percentage increases in mortality per degree fall in temperature were surprisingly greatest in countries with more mild climates. [1] The rate of EWM in the UK also appears higher than in countries with lower winter temperatures such as Finland and Denmark. [2] Such findings have led many to conclude that there is a great potential in the UK to reduce excess winter deaths.

Some argue that the high levels in the UK relate to poor insulation and housing standards resulting in low indoor temperatures, [3] [4] whilst others stress the importance of outdoor exposure. [5] Keatinge, [6] has argued strongly that campaigns remain overly fixated on indoor heating, when the cold stress experienced from minutes spent at a windy bus stop can exceed anything experienced indoors.

It is likely that both these variables play important roles in EWM. Research has also demonstrated that there is no clear link between these deaths and the usual measures of deprivation or social class. [7] [8] [9] In fact, it was found in one study that people in the lowest socio-economic groups do not necessarily live in cooler homes as housing association and local authority dwellings tend to be well heated and well-insulated, whereas large owner-occupier houses tend to be those which are harder to heat. [10] However, the present policy focus on fuel poverty or affordable warmth acknowledges that socio-economic factors do play a role in the health inequalities associated with EWM, even if this cannot be easily demonstrated by the available data. Reliance on public transport however (a feature of deprivation), is thought to increase exposure to outdoor cold.

Recent research has suggested a relationship between hospital admission rates and poverty using the fuel poverty risk index [11] and the Meteorological Office has done considerable work looking at temperature as a predictor of hospital admissions.

The strongest risk factor is age, with most studies showing EWM concentrated in people over 75. This would suggest that interventions to tackle winter deaths should focus on this age group — although there is a rationale for also focusing on the very young, and those with specific circumstances and conditions that make them more vulnerable to cold-related illness. The research also suggests that future activities should focus on the private housing sectors — both owner-occupiers and private rented accommodation. Older people living in older housing, are particularly at risk. [12]

Respiratory illness has a significantly higher excess winter death index than other illnesses and there is some national evidence that having an existing respiratory condition significantly increases the risk of winter death. A recent Nottingham Health Needs Assessment found that deaths from respiratory disease have an EWM index of around 43%, and that this was significantly higher than the indices of other disease categories. [13]

A report has shown that asthma patients without a written personal asthma action plan are four times more likely to have to be admitted to hospital, due to an asthma attack, than those who do. At the time of report's writing, only 16% of people with asthma in England have a written personal asthma action plan. [14]

The South East Public Health Observatory (SEPHO) report into EWM notes that there is a significantly greater increase in EWM ratios for care home residents. As care home residents generally lead a sheltered existence, protected from exposure to outdoor temperatures, damp housing or difficulties with heating their homes, it might be expected that EWM would be low for this group, when in fact, the opposite is true (another Winter mortality paradox). It is the case however, that people in care homes are likely to be the very oldest older people, many will have pre-existing conditions and they live in an enclosed space where infection can easily spread. Greater excess mortality amongst this group may also reflect seasonal patterns in care home use, for example, more patients being admitted to care homes shortly before death in the winter period. Whatever the explanation (and there are many), figures do demonstrate that the seasonal increase in mortality has a strong impact on care home residents. The report notes that guidance for care homes has been developed on dealing with heatwaves, and suggests that similar guidance for winter might also be beneficial. [12]

A range of research has argued that vaccination of health care workers is important to limit spread of flu amongst vulnerable patients in hospitals and other healthcare settings. [15] [16]

Figure 1: Epidemic curve of confirmed influenza cases.
Figure 1: Epidemic curve of confirmed influenza cases, Royal Liverpool University Hospital, and influenza-like illness rates in Liverpool between week 47/2008 and week 2/2009

A report from the North West Health Protection Unit (2009) [17] notes the importance of vaccination of staff. An outbreak of influenza occurred amongst patients and staff at an acute hospital in the North West of England in early December 2008. Over a three-week period in November/December 2008, rates of influenza-like illness in Liverpool increased from 26.7 per 100,000 population (in week 47) to 102.7 per 100,000 (in week 50). At the same time cases of influenza started presenting at the Royal Liverpool University Hospital. On 25th November a confirmed case of influenza, acquired in the hospital, was diagnosed on the haematology ward. The number of infections increased quickly until infection control and immunisation measures were put in place (Figure 1).

The outbreak illustrated how easily influenza can spread in a health care setting when virus is circulating in the community and staff vaccination levels are low. It was a notable success in the management of the outbreak that high levels of vaccination were achieved in a short period of time, helping to reduce the exposure of vulnerable patients in hospital despite the ongoing seasonal influenza activity in the community.


References

[1]   Healy J. Excess winter mortality in Europe: a cross country analysis identifying key risk factors Journal of Epidemiology & Community Health 2003; 57(10): 784-9.
[2]   Howden-Chapman P. Housing standards: a glossary of housing and health Journal of Epidemiology & Community Health 2004; 58(3): 162-8.
[3]   Clinch J, Healy J. Housing standards and excess winter mortality Journal of Epidemiology & Community Health 2000; 54(9): 719-20.
[4]   Blane D, Mitchell R, Bartley M. The inverse housing law and respiratory health Journal of Epidemiology & Community Health 2000; 54: 745-749.
[5]   Wilkinson P, Landon M, Armstrong B, et al. Cold comfort: The social and environmental determinants of excess winter deaths in England, 1986-96 2001; The Policy Press, Oxford.
[6]   Keatinge W. Winter deaths: warm housing is not enough British Medical Journal 2001; 323: 166.
[7]   Shah S, Peacock J. Deprivation and excess winter mortality Journal of Epidemiology & Community Health 1999; 53(8): 499-502.
[8]   Lawlor D, Maxwell R, Wheeler B. Rurality, deprivation, and excess winter mortality: an ecological study Journal of Epidemiology & Community Health 2002; 56(5): 373-4.
[9]   Gemmell I, McLoone P, Boddy F, et al. Seasonal variation in mortality in Scotland International Journal of Epidemiology 2000; 29(2): 274-9.
[10]   Hajat S, Kovats R, Lachowycz K. Heat-related and cold related deaths in England & Wales: who is at risk? Occupational and Environmental Medicine Journal 2007; 64: 93-100.
[11]   Rudge J, Gilchrist R. Excess winter morbidity among older people at risk of cold homes: a population based study in a London borough Journal of Public Health Medicine 2005; 27: 353-58.
[12]   Dinsdale H, Williams DE, Adur DF. Technical Report: Excess Winter Mortality 2006; South East public Health Observatory.
[13]   Howard R, Copping J. Excess Winter Deaths: A Health Needs Assessment for NHS Nottingham City 2010; Nottingham City Council. http://www.nottinghaminsight.org.uk/insight/docs/resources.ashx?f=REPORTS.R_10_1783&title=Excess_Winter_Deaths_Health_Needs_Assessment .
[14]   Asthma UK. The Asthma Divide - inequalities in asthma care for people with asthma in England 2007; Asthma UK. http://www.asthma.org.uk/document.rm?id=322 .
[15]   Wilde J, McMillan J, Serwint J, et al. Effectiveness of influenza vaccine in health care professionals: a randomized trial Journal of the American Medical Association 1999; 281: 908-13.
[16]   Hayward A, Harling R, Wetten S, et al. Effectiveness of an influenza vaccine programme for care home staff to prevent death, morbidity, and health service use among residents: cluster randomised controlled trial British Medical Journal 2006; 333: 1241-7.
[17]   Health Protection Agency. Health Protection Weekly News Report 2009;