cold and health james goodwin head of research
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Cold and Health James Goodwin Head of Research. Hippocrates 400BC. On airs, waters, and places. Whoever wishes to investigate medicine properly, should proceed thus: - PowerPoint PPT PresentationTRANSCRIPT
Hippocrates 400BC
• Whoever wishes to investigate medicine properly, should proceed thus: in the first place to consider the seasons of the year, and what effects each of them produces for they are not at all alike, but differ much from themselves in regard to their changes.
• Secondly he must study the warm and the cold winds, both those which are common to every country and those peculiar to a particular locality …
On airs, waters, and places
Five Vital Questions
• Why does health deteriorate in the winter?
• Does age make a difference?
• What is ‘Excess Winter Mortality’?
• What are its causes?
• Can we do anything about it?
Why does health deteriorate in the winter
• Ill-health is associated with a number of winter factors, notably reducing photo-period and cold temperature
• We have tropical physiology
• Darkness is associated with emotional responses and mental health
• Cold is associated with physical and psychological responses
Does age make a difference?
• Vulnerability to cold increases with age:– Declining immune system– Lower physiological reserve– Slower and less precise bodily responses,
particularly temperature control, respiratory and cardio-vascular systems
• The change is progressive and variable but real decrements start at about 75 years and accelerate thereafter
Skin Temperature (Finger) in Young (n=9) and Elderly (n=9) Subjects at 6 and 21C
0 20 40 60 80
% VO2 max
12
14
16
18
20
22
24
26
28
30
32
Tem
pe
ratu
re o
C
Y Tf 6oC
Y Tf 21oC
E Tf 21oC
E Tf 6oC
Excess Winter Mortality
• EWM is the number of deaths occurring between 1st December and 31st March less the number of deaths in the rest of the year
• Since 1841 there have been approximately 3 million avoidable deaths in the older population in the winter
• For every 1◦C reduction in the average ambient temperature in the winter, there are 8,000 more deaths (Curwen M 1997)
Ratio
of o
bser
ved
to e
xpec
ted
deat
hs
Maximum daily temperature C0 10 20 30
.75
1
1.25
1.5
Gradient represents
strength of low temperature-
mortality relationship
Frequency distribution of max. temperatures
Mortality and temperature distribution
Excess Winter Deaths
LONDON, 1986-96
D
AIL
Y D
EA
TH
S
01jan1986 01jan1988 01jan1990 01jan1992 01jan1994 01jan1996
0
100
200
300
400
Inside vs Outside Cold
• Few older people live in homes without central heating but many restrict their use of it mainly on grounds of cost (fuel poverty)
• Moving from a cold home to outside cold carriessignificantly more risk to health than moving from a warm home
• Relatively minor cold exposures in daily life are sufficient to induce significant hypertension and haemoconcentration
• Linear inverse relationship between activitylevels and indoor cold with increased outdoorexcursions in older people living in cold homes
Inside ColdR
ela
tive r
isk o
f d
eath
Date1Jan 1Apr 1Jul 1Oct 31Dec
.8
1
1.2
1.4
1.6 Coldest 25% of homes
Warmest 25% of homes
Euro-winter Study
Notable Findings• Percentage increases in all cause mortality per 1C (below
18C) are greater in warm than in cold regions (eg Athens vs south Finland)
• High indices of cold related mortality are associated with– high mean winter temperatures– low living room temperatures– limited bedroom heating– low clothing protection– physical activity
• Lag effects exist between onset of cold and death
Causes of Winter Death
• Less than 1% due to hypothermia
• Small number of deaths due to influenza, except in epidemic years (eg winter ‘89/90)
• Respiratory illness (eg COPD, bronchitis) 12 day’ lag effect’; deaths declining due to warmer homes
• Thrombotic illness (eg MI, stroke) 3-7 day ‘lag effect’; deaths show little change over time and are related to outdoor cold exposure
Aderdeen,Scotland
0-8°C in JanuaryYakutsk ,Siberia
-26.6°C
All cause mortality unaffected
Kuwait
8-18°C in January
50 Year Regression DataExcess Winter Mortality 1950 - 2010
0
20,000
40,000
60,000
80,000
100,000
120,000
1950
/195
119
52/195
319
54/195
519
56/195
719
58/195
919
60/196
119
62/196
319
64/196
519
66/196
719
68/196
919
70/197
119
72/197
319
74/197
519
76/197
719
78/197
919
80/198
119
82/198
319
84/198
519
86/198
719
88/198
919
90/199
119
92/199
319
94/199
519
96/199
719
98/199
920
00/200
120
02/200
320
04/200
520
06/200
720
08/200
9
Summary of the Evidence - Cold
• Extremes of cold incur high rates of morbidity and mortality in older people via respiratory and thrombotic illness• Respiratory mortality appears to be falling due to warmer homes •Indoor and outdoor cold are independent risk factors• Predisposing factors appear to be:
– age (frailty, co-morbidity)– home conditions– high-risk behaviour – social isolation– limited access to health and social care– social inequality