485
rectly predicted bilateral hyperplasia in the eighth. Like Fukuchi et al.,z4 we found that correct location was possible even when both adrenal veins could not be cannulated. Because of the disappointing yield from venography and its risks, it may be that contrast should only be used during adrenal-vein .catheterisation to the extent necessary for the accurate placement of catheters for collection of plasma-samples. Even though the risks of adrenal-vein catheterisation can be minimised in this way, the investigation remains invasive and uncomfortable for the patient and is expensive in medical time. We have found that the iodocholesterol scan correctly locates the tumour in the majority of patients.25,26 With the use of dexamethasone suppression and selenium-75 labelled cholesterol it may be that the reliability of the scintiscan will be improved further in the future, and this non-invasive procedure will make adrenal-vein catheterisation unnecessary. Unfortunately this has not yet been established, and our present practice is to perform both tests in all patients with biochemical primary aldosteronism, unless the scintiscan reveals unequivocally which side the tumour is on. When the diagnosis of adenoma and clear identification of which gland is affected is made by these tests, then the results of surgery are excellent and the risks very small. We would, therefore, disagree with SleightlO and prefer surgery to a lifetime of medical treatment, with its problems of drug side-effects, drug compliance, doctor-dependence, and implications for employment. Our finding that 30% of patients with adenoma remained mildly hypertensive after surgery is in keeping with the observations of Conn 17 and of Biglieri et aI. 28 who found 36.5% and 40%, respectively, to remain mildly hypertensive. Only 1 of our patients with adenoma required antihypertensive treatment after surgery. We thank the physicians of the Northern Region for referring patients, Mrs Valerie Robson for renin and aldosterone measurements, and Mrs Rita Grieveson for secretarial help.
Requests for reprints should be addressed to R. W., Department of Nephrology, Freeman Hospital, Heaton, Newcastle upon Tyne, NE7 lDN. REFERENCES 1. Conn, J. W. J. lab. clin. Med. 1955, 45, 3. 2. Berglund, G., Andersson, O., Wilhelmsen, L. Br. med. J. 1976, ii, 554. 3. Conn, J. W., Knopf, R. F., Nesbit, R. M. in Aldosterone (edited by E. E Baulieu and P. Robel); p. 327. Oxford, 1964. 4. Baglin, A., Weiss, Y., Safar, M., Milliez, P. Nouv. Presse Méd. 1973, 2, 295. 5. Baxter, R. H., Wang, I. Scott. med. J. 1974, 19, 161. 6. Aloia, J.F., Beuton, G. Am. J. med. Sci. 1974, 268, 241. 7 Spark, R. F., Melby, J. C. Ann. intern Med. 1968, 68, 685. 8. Brown, J. J., Davies, D. L., Ferriss, J. B., Fraser, R., Haywood, E., Lever, A. F., Robertson, J. I. S. Br. med. J. 1972, i, 729. 9 Kremer, D., Boddy, K., Brown, J. J., Davies, D. L., Fraser, R., Lever; A. F., Morton, J. J., Robertson, J. I. S. Clin. Endocr. 1977, 7, 151. 10. Sleight, P. Medicine, 1977, no. 27, 1431. 11. Fraser, R., Guest, S., Young, J. Clin. Sci. mol. Med. 1973, 45, 411. 12. Snow, M. H., Nicol, P., Wilkinson, R., Hall, R., Johnston, I. D. A., Hacking, P M., Rolland, C. Br. med. J. 1976, i, 1125. 13. Conn, J. W., Cohen, E. L., Rovner, D. R., Nesbit, R. M. J. Am. med. Ass.
1965, 193, 200. 14. Baer, L., Sommers, S. G., Krakoff, L. R., Newton, M. A., Laragh, J. H. Circ. Res. 1970, suppl. 1, I-203. 15 Aitchison, J., Brown, J. J., Ferriss, J. B., et al. Am. heart J. 1971, 82, 660. 16. Ganguly, A., Melada, G. A., Luetscher, J. A., Dowdy, A. J. J. clin. Endocr Metab. 1973, 37, 765. 17 Biglieri, E. G., Schamberlan, M., Brust, N., Chang, B., Hogan, M. Circ. Res 1974, 34, suppl. 1, 1183. 18. Bayliss, R. I. S., Edwards, Q. M., Starer, F. Br. J. Radiol. 1970, 43, 531. 19 Eagan, R. T., Page, M. I. J. Am. med. Ass. 1971, 215, 115. 20 Kahn, P C., Kelleher, D., Egdahl, R. H., Melby, J. C. Radiology, 1971, 101, 71
Public Health INCREASE IN DEATHS FROM ISCHÆMIC HEART-DISEASE AFTER BLIZZARDS ROGER I. GLASS
MATTHEW M. ZACK,
JR.
Chronic Diseases Division, Bureau of Epidemiology, Center for Disease Control, Atlanta, Georgia, U.S.A.
Death certificates in eastern Massachusetts after six blizzards in 1974-78, inthe record blizzard of Feb. 6, 1978, were examcluding ined to identify the effect on mortality of these storms. The total number of deaths was significantly higher (8%) in a "blizzard week" than in the preceding and subsequent (control) weeks (114·1 vs. 105·3 deaths per day). Deaths from ischæmic heart-disease (I.H.D.), which rose significantly by 22% in the blizzard week from 36·7 to 44·6 deaths per day, accounted for 90% of the excess total deaths. The increase was greater in males than in females (30% vs. 12%), and in both sexes there was no difference in the distribution of deaths by age between the blizzard and control weeks. I.H.D. deaths were increased for 8 days after a snowstorm, suggesting that the effect was related to activities such as snow shovelling rather than the storm itself. The identification of those at increased risk of I.H.D. death after major snowstorms and of the circumstances surrounding such deaths could lead to public-health measures to reduce these weatherrelated premature deaths.
Summary
INTRODUCTION
ON Feb. 6 and 7, 1978, the largest local snowfall of the century immobilised eastern Massachusetts and led the governor to declare a full traffic ban and a 1-week cancellation of all non-essential work. The Center for Disease Control (C.D.C.) was asked to assess the health effects of the storm in the snowbound areas. As part of this effort, we analysed death certificates from eastern Massachusetts to identify trends in mortality related to 6 major blizzards (including the record blizzard of 1978). We were particularly concerned with cardiovascular mortality, since snowstorms are known to be associated with attacks of angina pectoris in patients with pre-existing coronary-artery disease1,2 either as a result of cold exposure alone or after exertion that could have been tolerated at a higher temperature.3,4 Furthermore, winter and colci weather each brincr an
21. Davidson,
excess
of carciin-
J. K., Morley, P., Hurley, G. D., Holford, N. G. H. Br. J. Radiol. 1975, 48, 435. 22. Scoggins, B. A., Oddie, C. J., Hare, W. S. C., Coghlan, J. P., Ann. intern. Med. 1972, 76, 891. 23. Horton, R., Fink, E. ibid. 1972, 76, 885. 24. Fukuchi, S., Takenoughi, T., Nakajima, K., Watanabe, H., Sugita, A. Clin. Sci. mol. Med. 1975, 49, 187. 25. Seabold, J. E., Cohen, E. L., Beieiwalters, W. H., Hinerman, D. L., Bishiyama, R. H., Bookstem, J. J., Ice, R. D., Balachandran, S. J. clin. Endocr. Metab. 1976, 42, 41. 26. Hogan, M. J., McRae, J., Schambelan, M., Biglieri, E. G. New Engl. J. Med. 1976, 294, 410. 27. Conn, J. W. Harvey Lect. 1967, 62, 257. 28. Biglieri, E. G., Schambelan, M., Slaton, P. E., Stockigt, J. R. Circ. Res. 1970, suppl. 1, I-195.
486 TABLE III-SEX DISTRIBUTION OF LH.D. DEATHS IN
vascular deaths and the impact of snow as an assdciatec factor has not been properly assessed.5-8 Tempora trends in excess mortality after major snowstorms migh lead to the identification of high-risk groups and of pree cipitating activities, and ultimately to the formulation o public-health programmes to reduce these prematur weather-related deaths.
AND
12
6
BLIZZARD
CONTROL WEEKS
MATERIALS AND METHODS
*F test for the comparison of mean deaths per week and control weeks.
The Office of State Health Planning of the Massachusetts Department of Public Health provided information abou death certificates (without names) from December, 197 through February, 1978; for Health Service Areas IlI-V] which include Boston and its suburbs. We analysed all death and deaths for 8 specific diagnoses groupéd according to th International Classification of Diseases A codes (8th revision cancer (140-209); ischaemic heart-disease (410-414); cerebr( vascular disease (430-438); pneumonia and influenz TABLE
-
after this blizzard week. We excluded from analysis blizzards that coincided with an influenza epidemic in New England identified from the C.D.C.’s annual reports9 and blizzards that occurred within 2 weeks of each other and had overlapping control periods. In all, six blizzards met the criteria for inclusion and three did not-one occurred at the peak of an influenza epidemic (Jan. 20, 1978) and two occurred within 2 weeks of each other (Dec. 29,1976 and Jan. 7,1977). We used Student’s t test to determine significant differences in mean daily number of deaths for each diagnosis between the blizzard and control weeks. We analysed data on each of the six blizzards separately and then together. Extension of the control period to include the 2 weeks before and 2 weeks after the blizzard week did not affect the results of our original
I-DEATHS/DAY BY DIAGNOSTIC CATEGORY IN
WEEK FEB.
6-12, 1978
VS. ONE
by sex in blizzard
BLIZZARD WEEK BEFORE AND ONE WEEK
analyses. 1-week
adequate to screen for major health not to identify the specific days on which the effect occurred. For diagnoses showing a significant trend in the blizzard week, we plotted the daily number of deaths for the 4-week period extending from 1 week before the blizzard to 3 weeks after. For the six blizzards, the mean daily number of deaths during the two weeks after the first day of the blizzard (weeks 2 and 3) were compared with the mean daily number of deaths in weeks 1 and 4. periods
were
effects of blizzards but
of I.H.D. deaths occurred in the blizzard F statistics to test differences in the age and used 2 and sex distribution of individuals who died of I.H.I), in the blizzard week and in the control period. Since low temperatures have been associated with angina and with excess I.H.D. deaths, we compared the mean daily temperatures in the blizzard and the control weeks and estimated by linear regression analysis the nuriiber of deaths during the blizzard period attributable to temperature differences.values of less than or equal to 0 - 0were regarded as statistically significant. Because
week, *Based on unpaired Student’s t
(470-474, 480-486);
test.
motor
vehicle accidehts
(820-827); noncompli-
vehicle accidents (800-819, 828-949); surgical cations (930-936); and suicide (950-959), motor
The National Weather Service supplied data on the average daily temperature and snowfall at Logan International Airport in Boston during the same period. We defined a blizzard arbitrarily as a 2-day period during December, January, or February when at least 8 in (20 cni) of snow fell. Because a blizzard might affect mortality patterns for some time after the immediate snowfall, and because the daily number of deaths in some of our diagnostic categories were small and varied by day of the week, we defined a "blizzard Week" as the 7-day period beginning with the first day of snowfall. We compared the average daily number of deaths in this blizzard week with that in a control period-i.e., the week before and the week TABLE II-TOTAL DEATHS AND I.H.D. DEATHS PER DAY IN
RESULTS
blizzard week Feb. 6-12, 1978 there was r.H.D. deaths (pro-03) and a 36% decrease in pneumonia and influenza deaths (rio’04) (table i). For all six blizzards, the total number of deaths from all causes and of LH.D. deaths rose consistently during the blizzard week (table n). Overall, total deaths
During the
a
24% increase in
EASTERN MASSACHUSETTS FOR 6
1974-78
*Control weeks=one week before and one week after the blizzard week.
tBased on unpaired Student’s t test.
an excess
we
BLIZZARD WEEKS AND
12
CONTROL
WEEKS,*
487
early but, rather, those whose deaths would not have occurred in the immediate future. The concentration of this excess among men might be explained by snow shovellingll or by increased exposure to the cold weather because of the problems caused by deep snow. An increased number of births nine months after the 1978 blizzard suggests that increased sexual activity in this period might also have contributed to excess
DAYS
’MEAN t STANDARD ERROR BASED ON 2 CONTROL PERIODS PER BLIZZARD E=3 CONTROL PERIODS
Average number of I.H.D. deaths
per
day after
6 blizzards it
eastern Massachusetts (1974-78).
day rose 8% (P=0.004) during the blizzard week, an which was mainly the result of a 22% rise (P=7xl0) in I.H.D. deaths. On average, there were 61.6 more deaths than expected in the blizzard week of which 55.3 (90%) were attributed to I.H.D. Excess I.H.D. mortality primarily affected males (P=0.002), in whom there was a 30% increase during blizzard weeks (table III). The 12% increase among women was not statistically significant (P=0.078). The age distribution by sex of I.H.D. deaths did not change during blizzard periods. Excess deaths occurred throughout the 8 days after the storm and not only during the first 2 days of the storm itself (see accompanying figure). Although the average daily temperature during the six blizzard weeks (25°F, -4°C) averaged 4°F (22°C) less than the control periods (P=0.02), there was no significant association between LH.D. mortality and temperature through the range of temperatures observed in this study. per
excess
DISCUSSION
This study demonstrates a significant increase of total deaths and of LH.D. deaths in the week after a major blizzard in eastern Massachusetts. This excess is independent of temperature variations and affects primarily males. These findings are consistent with widely held clinical impressions relating snowstorms to various manifestations of LH.D. and with Rogot’s findings8 of excess I.H.D.
mortality on snow days.
snowstorms
We thank Elliot Stone and Pam Lowry for help with the death certificate tapes, Dr Barbara Stoll, Dr Stephen Thacker, Dr David Fraser, Dr Michael Gregg, Dr Philip Landrigan, Dr Clark Heath, Dr Lyle Conrad, and Dr Stanley Music for assistance, Mr William Wilcox, Administrator, Federal Disaster Assistance Administration, for support, and Mrs Rose Taylor and Mrs Loraine Good for help in preparing the article.
Requests for reprints should be addressed to R. 1. G., Special Studies Branch, Chronic Diseases Division, Center for Disease Central, 1600 Clifton Road, N.E., Atlanta, Georgia 30333, U.S.A. REFERENCES
,
lasted 1 or 2 days, and cannot for the deaths account throughout the following week. Incorrect diagnoses could explain part of the increase in I.H.D. deaths in the first days after the snowfall but cannot explain the persistent excess nor the increase in total deaths. Transport, communication, and isolation problems of the elderly and the poor might have made this group particularly susceptible to failures of home heating and emergency transport or to inadequate provision of food and medicines. There was no change, however, in the age-distribution of I.H.D. deaths suggesting that older people were not more likely to be affected. Furthermore, the absence of a dip in daily mortality after the excess had occurred suggests that those who died were not people whose imminent death was precipitated The
I.H.D.12,13
83 million out of 202 million Americans live in areas at high risk of severe snowstorms and another 62 million live in medium-risk areas. 14 If a major blizzard such as those studied here occurred in the high-risk areas once a year, approximately 1200 blizzard-related deaths could be expected yearly. This estimate assumes an 8% excess mortality in the week after the blizzard and does not take into account area differences in age, sex, and rural vs. urban residence. It further assumes that more frequent but smaller snowstorms do not lead to excess deaths. (Yearly deaths in the U.S.A. [1970] are 1 900 000, so weekly deaths in high-risk areas come to 15 000. An 8% excess mortality would then be 1200.) Specific risk factors associated with these deaths might include personal factors such as pre-existing heart-disease, excess physical or sexual activity, prolonged exposure to cold, or social factors such as interrupted access to medical care, food, medications, or heating oil. Identification of these risk factors might permit implementation of public-health measures directed at high-risk individuals. Although we are not certain whether persons with pre-existing heart-disease accounted for the increase in deaths observed in this study, snowstorms may precipitate angina in this group, and such people should be warned about the risks of exposure to cold and overexertion. Medical services should plan for more I.H.D. patients in the high-risk periods associated with blizzards.
W., Logue, R. B., Walter, P. F. in The Heart (edited by J. W. Hurst); p. 1175. New York, 1978. 2. Freedberg, A. S., Spiegl, E. D., Riseman, J. E. F. Am. Heart J. 1944, 27, 1. Hurst, J.
611.
Epstein, S. E., Stampfer, M., Beiser, G. S., Goldstein, R. E., Braunwald, E. New Engl. J. Med. 1969, 280, 7. 4. Hattenhauer, M., Neill, W. A. Circulation, 1975, 51, 1053. 5. Rogot, E., Fabsitz, R., Feinleib, M. Am. J. Epidem. 1976, 103, 198. 6. Rosenwaike, I. J. Am. stat. Ass. 1966, 61, 706. 7. Kutschenreuter, P. H. Trans N.Y. Acad. Sci. 1959, 22, 126. 8. Rogot, E. Publ. Hlth Rep. 1974, 89, 330. 9. Center for Disease Control. Reported Morbidity and Mortality in the United States. DHEW/USPHS/CDC Atlanta (5 volumes), 1973, 22, 47; 1974, 23, 48; 1975, 24, 50; 1976, 25, 54; 1977, 26, 62. 10. Armitage, P. Statistical Methods in Medical Research; Oxford, 1977. 11. Burgess, A. M. Rhode Island med. J. 1965, 68, 131. 12. Atlanta Constitution. Nov. 18, 1978, p. 3B. 13. Heggtveit, H. A. Am. Heart J. 1965, 69, 287. 3.
14.
H. C., Knowles, B. A. Urban Snow Hazard in the United States: A Research Assessment. U.S. Department of Commerce, June, 1975 PB
Cochrane,
242 977.
rectly predicted bilateral hyperplasia in the eighth. Like Fukuchi et al.,z4 we found that correct location was possible even when both adrenal veins could not be cannulated. Because of the disappointing yield from venography and its risks, it may be that contrast should only be used during adrenal-vein .catheterisation to the extent necessary for the accurate placement of catheters for collection of plasma-samples. Even though the risks of adrenal-vein catheterisation can be minimised in this way, the investigation remains invasive and uncomfortable for the patient and is expensive in medical time. We have found that the iodocholesterol scan correctly locates the tumour in the majority of patients.25,26 With the use of dexamethasone suppression and selenium-75 labelled cholesterol it may be that the reliability of the scintiscan will be improved further in the future, and this non-invasive procedure will make adrenal-vein catheterisation unnecessary. Unfortunately this has not yet been established, and our present practice is to perform both tests in all patients with biochemical primary aldosteronism, unless the scintiscan reveals unequivocally which side the tumour is on. When the diagnosis of adenoma and clear identification of which gland is affected is made by these tests, then the results of surgery are excellent and the risks very small. We would, therefore, disagree with SleightlO and prefer surgery to a lifetime of medical treatment, with its problems of drug side-effects, drug compliance, doctor-dependence, and implications for employment. Our finding that 30% of patients with adenoma remained mildly hypertensive after surgery is in keeping with the observations of Conn 17 and of Biglieri et aI. 28 who found 36.5% and 40%, respectively, to remain mildly hypertensive. Only 1 of our patients with adenoma required antihypertensive treatment after surgery. We thank the physicians of the Northern Region for referring patients, Mrs Valerie Robson for renin and aldosterone measurements, and Mrs Rita Grieveson for secretarial help.
Requests for reprints should be addressed to R. W., Department of Nephrology, Freeman Hospital, Heaton, Newcastle upon Tyne, NE7 lDN. REFERENCES 1. Conn, J. W. J. lab. clin. Med. 1955, 45, 3. 2. Berglund, G., Andersson, O., Wilhelmsen, L. Br. med. J. 1976, ii, 554. 3. Conn, J. W., Knopf, R. F., Nesbit, R. M. in Aldosterone (edited by E. E Baulieu and P. Robel); p. 327. Oxford, 1964. 4. Baglin, A., Weiss, Y., Safar, M., Milliez, P. Nouv. Presse Méd. 1973, 2, 295. 5. Baxter, R. H., Wang, I. Scott. med. J. 1974, 19, 161. 6. Aloia, J.F., Beuton, G. Am. J. med. Sci. 1974, 268, 241. 7 Spark, R. F., Melby, J. C. Ann. intern Med. 1968, 68, 685. 8. Brown, J. J., Davies, D. L., Ferriss, J. B., Fraser, R., Haywood, E., Lever, A. F., Robertson, J. I. S. Br. med. J. 1972, i, 729. 9 Kremer, D., Boddy, K., Brown, J. J., Davies, D. L., Fraser, R., Lever; A. F., Morton, J. J., Robertson, J. I. S. Clin. Endocr. 1977, 7, 151. 10. Sleight, P. Medicine, 1977, no. 27, 1431. 11. Fraser, R., Guest, S., Young, J. Clin. Sci. mol. Med. 1973, 45, 411. 12. Snow, M. H., Nicol, P., Wilkinson, R., Hall, R., Johnston, I. D. A., Hacking, P M., Rolland, C. Br. med. J. 1976, i, 1125. 13. Conn, J. W., Cohen, E. L., Rovner, D. R., Nesbit, R. M. J. Am. med. Ass.
1965, 193, 200. 14. Baer, L., Sommers, S. G., Krakoff, L. R., Newton, M. A., Laragh, J. H. Circ. Res. 1970, suppl. 1, I-203. 15 Aitchison, J., Brown, J. J., Ferriss, J. B., et al. Am. heart J. 1971, 82, 660. 16. Ganguly, A., Melada, G. A., Luetscher, J. A., Dowdy, A. J. J. clin. Endocr Metab. 1973, 37, 765. 17 Biglieri, E. G., Schamberlan, M., Brust, N., Chang, B., Hogan, M. Circ. Res 1974, 34, suppl. 1, 1183. 18. Bayliss, R. I. S., Edwards, Q. M., Starer, F. Br. J. Radiol. 1970, 43, 531. 19 Eagan, R. T., Page, M. I. J. Am. med. Ass. 1971, 215, 115. 20 Kahn, P C., Kelleher, D., Egdahl, R. H., Melby, J. C. Radiology, 1971, 101, 71
Public Health INCREASE IN DEATHS FROM ISCHÆMIC HEART-DISEASE AFTER BLIZZARDS ROGER I. GLASS
MATTHEW M. ZACK,
JR.
Chronic Diseases Division, Bureau of Epidemiology, Center for Disease Control, Atlanta, Georgia, U.S.A.
Death certificates in eastern Massachusetts after six blizzards in 1974-78, inthe record blizzard of Feb. 6, 1978, were examcluding ined to identify the effect on mortality of these storms. The total number of deaths was significantly higher (8%) in a "blizzard week" than in the preceding and subsequent (control) weeks (114·1 vs. 105·3 deaths per day). Deaths from ischæmic heart-disease (I.H.D.), which rose significantly by 22% in the blizzard week from 36·7 to 44·6 deaths per day, accounted for 90% of the excess total deaths. The increase was greater in males than in females (30% vs. 12%), and in both sexes there was no difference in the distribution of deaths by age between the blizzard and control weeks. I.H.D. deaths were increased for 8 days after a snowstorm, suggesting that the effect was related to activities such as snow shovelling rather than the storm itself. The identification of those at increased risk of I.H.D. death after major snowstorms and of the circumstances surrounding such deaths could lead to public-health measures to reduce these weatherrelated premature deaths.
Summary
INTRODUCTION
ON Feb. 6 and 7, 1978, the largest local snowfall of the century immobilised eastern Massachusetts and led the governor to declare a full traffic ban and a 1-week cancellation of all non-essential work. The Center for Disease Control (C.D.C.) was asked to assess the health effects of the storm in the snowbound areas. As part of this effort, we analysed death certificates from eastern Massachusetts to identify trends in mortality related to 6 major blizzards (including the record blizzard of 1978). We were particularly concerned with cardiovascular mortality, since snowstorms are known to be associated with attacks of angina pectoris in patients with pre-existing coronary-artery disease1,2 either as a result of cold exposure alone or after exertion that could have been tolerated at a higher temperature.3,4 Furthermore, winter and colci weather each brincr an
21. Davidson,
excess
of carciin-
J. K., Morley, P., Hurley, G. D., Holford, N. G. H. Br. J. Radiol. 1975, 48, 435. 22. Scoggins, B. A., Oddie, C. J., Hare, W. S. C., Coghlan, J. P., Ann. intern. Med. 1972, 76, 891. 23. Horton, R., Fink, E. ibid. 1972, 76, 885. 24. Fukuchi, S., Takenoughi, T., Nakajima, K., Watanabe, H., Sugita, A. Clin. Sci. mol. Med. 1975, 49, 187. 25. Seabold, J. E., Cohen, E. L., Beieiwalters, W. H., Hinerman, D. L., Bishiyama, R. H., Bookstem, J. J., Ice, R. D., Balachandran, S. J. clin. Endocr. Metab. 1976, 42, 41. 26. Hogan, M. J., McRae, J., Schambelan, M., Biglieri, E. G. New Engl. J. Med. 1976, 294, 410. 27. Conn, J. W. Harvey Lect. 1967, 62, 257. 28. Biglieri, E. G., Schambelan, M., Slaton, P. E., Stockigt, J. R. Circ. Res. 1970, suppl. 1, I-195.
486 TABLE III-SEX DISTRIBUTION OF LH.D. DEATHS IN
vascular deaths and the impact of snow as an assdciatec factor has not been properly assessed.5-8 Tempora trends in excess mortality after major snowstorms migh lead to the identification of high-risk groups and of pree cipitating activities, and ultimately to the formulation o public-health programmes to reduce these prematur weather-related deaths.
AND
12
6
BLIZZARD
CONTROL WEEKS
MATERIALS AND METHODS
*F test for the comparison of mean deaths per week and control weeks.
The Office of State Health Planning of the Massachusetts Department of Public Health provided information abou death certificates (without names) from December, 197 through February, 1978; for Health Service Areas IlI-V] which include Boston and its suburbs. We analysed all death and deaths for 8 specific diagnoses groupéd according to th International Classification of Diseases A codes (8th revision cancer (140-209); ischaemic heart-disease (410-414); cerebr( vascular disease (430-438); pneumonia and influenz TABLE
-
after this blizzard week. We excluded from analysis blizzards that coincided with an influenza epidemic in New England identified from the C.D.C.’s annual reports9 and blizzards that occurred within 2 weeks of each other and had overlapping control periods. In all, six blizzards met the criteria for inclusion and three did not-one occurred at the peak of an influenza epidemic (Jan. 20, 1978) and two occurred within 2 weeks of each other (Dec. 29,1976 and Jan. 7,1977). We used Student’s t test to determine significant differences in mean daily number of deaths for each diagnosis between the blizzard and control weeks. We analysed data on each of the six blizzards separately and then together. Extension of the control period to include the 2 weeks before and 2 weeks after the blizzard week did not affect the results of our original
I-DEATHS/DAY BY DIAGNOSTIC CATEGORY IN
WEEK FEB.
6-12, 1978
VS. ONE
by sex in blizzard
BLIZZARD WEEK BEFORE AND ONE WEEK
analyses. 1-week
adequate to screen for major health not to identify the specific days on which the effect occurred. For diagnoses showing a significant trend in the blizzard week, we plotted the daily number of deaths for the 4-week period extending from 1 week before the blizzard to 3 weeks after. For the six blizzards, the mean daily number of deaths during the two weeks after the first day of the blizzard (weeks 2 and 3) were compared with the mean daily number of deaths in weeks 1 and 4. periods
were
effects of blizzards but
of I.H.D. deaths occurred in the blizzard F statistics to test differences in the age and used 2 and sex distribution of individuals who died of I.H.I), in the blizzard week and in the control period. Since low temperatures have been associated with angina and with excess I.H.D. deaths, we compared the mean daily temperatures in the blizzard and the control weeks and estimated by linear regression analysis the nuriiber of deaths during the blizzard period attributable to temperature differences.values of less than or equal to 0 - 0were regarded as statistically significant. Because
week, *Based on unpaired Student’s t
(470-474, 480-486);
test.
motor
vehicle accidehts
(820-827); noncompli-
vehicle accidents (800-819, 828-949); surgical cations (930-936); and suicide (950-959), motor
The National Weather Service supplied data on the average daily temperature and snowfall at Logan International Airport in Boston during the same period. We defined a blizzard arbitrarily as a 2-day period during December, January, or February when at least 8 in (20 cni) of snow fell. Because a blizzard might affect mortality patterns for some time after the immediate snowfall, and because the daily number of deaths in some of our diagnostic categories were small and varied by day of the week, we defined a "blizzard Week" as the 7-day period beginning with the first day of snowfall. We compared the average daily number of deaths in this blizzard week with that in a control period-i.e., the week before and the week TABLE II-TOTAL DEATHS AND I.H.D. DEATHS PER DAY IN
RESULTS
blizzard week Feb. 6-12, 1978 there was r.H.D. deaths (pro-03) and a 36% decrease in pneumonia and influenza deaths (rio’04) (table i). For all six blizzards, the total number of deaths from all causes and of LH.D. deaths rose consistently during the blizzard week (table n). Overall, total deaths
During the
a
24% increase in
EASTERN MASSACHUSETTS FOR 6
1974-78
*Control weeks=one week before and one week after the blizzard week.
tBased on unpaired Student’s t test.
an excess
we
BLIZZARD WEEKS AND
12
CONTROL
WEEKS,*
487
early but, rather, those whose deaths would not have occurred in the immediate future. The concentration of this excess among men might be explained by snow shovellingll or by increased exposure to the cold weather because of the problems caused by deep snow. An increased number of births nine months after the 1978 blizzard suggests that increased sexual activity in this period might also have contributed to excess
DAYS
’MEAN t STANDARD ERROR BASED ON 2 CONTROL PERIODS PER BLIZZARD E=3 CONTROL PERIODS
Average number of I.H.D. deaths
per
day after
6 blizzards it
eastern Massachusetts (1974-78).
day rose 8% (P=0.004) during the blizzard week, an which was mainly the result of a 22% rise (P=7xl0) in I.H.D. deaths. On average, there were 61.6 more deaths than expected in the blizzard week of which 55.3 (90%) were attributed to I.H.D. Excess I.H.D. mortality primarily affected males (P=0.002), in whom there was a 30% increase during blizzard weeks (table III). The 12% increase among women was not statistically significant (P=0.078). The age distribution by sex of I.H.D. deaths did not change during blizzard periods. Excess deaths occurred throughout the 8 days after the storm and not only during the first 2 days of the storm itself (see accompanying figure). Although the average daily temperature during the six blizzard weeks (25°F, -4°C) averaged 4°F (22°C) less than the control periods (P=0.02), there was no significant association between LH.D. mortality and temperature through the range of temperatures observed in this study. per
excess
DISCUSSION
This study demonstrates a significant increase of total deaths and of LH.D. deaths in the week after a major blizzard in eastern Massachusetts. This excess is independent of temperature variations and affects primarily males. These findings are consistent with widely held clinical impressions relating snowstorms to various manifestations of LH.D. and with Rogot’s findings8 of excess I.H.D.
mortality on snow days.
snowstorms
We thank Elliot Stone and Pam Lowry for help with the death certificate tapes, Dr Barbara Stoll, Dr Stephen Thacker, Dr David Fraser, Dr Michael Gregg, Dr Philip Landrigan, Dr Clark Heath, Dr Lyle Conrad, and Dr Stanley Music for assistance, Mr William Wilcox, Administrator, Federal Disaster Assistance Administration, for support, and Mrs Rose Taylor and Mrs Loraine Good for help in preparing the article.
Requests for reprints should be addressed to R. 1. G., Special Studies Branch, Chronic Diseases Division, Center for Disease Central, 1600 Clifton Road, N.E., Atlanta, Georgia 30333, U.S.A. REFERENCES
,
lasted 1 or 2 days, and cannot for the deaths account throughout the following week. Incorrect diagnoses could explain part of the increase in I.H.D. deaths in the first days after the snowfall but cannot explain the persistent excess nor the increase in total deaths. Transport, communication, and isolation problems of the elderly and the poor might have made this group particularly susceptible to failures of home heating and emergency transport or to inadequate provision of food and medicines. There was no change, however, in the age-distribution of I.H.D. deaths suggesting that older people were not more likely to be affected. Furthermore, the absence of a dip in daily mortality after the excess had occurred suggests that those who died were not people whose imminent death was precipitated The
I.H.D.12,13
83 million out of 202 million Americans live in areas at high risk of severe snowstorms and another 62 million live in medium-risk areas. 14 If a major blizzard such as those studied here occurred in the high-risk areas once a year, approximately 1200 blizzard-related deaths could be expected yearly. This estimate assumes an 8% excess mortality in the week after the blizzard and does not take into account area differences in age, sex, and rural vs. urban residence. It further assumes that more frequent but smaller snowstorms do not lead to excess deaths. (Yearly deaths in the U.S.A. [1970] are 1 900 000, so weekly deaths in high-risk areas come to 15 000. An 8% excess mortality would then be 1200.) Specific risk factors associated with these deaths might include personal factors such as pre-existing heart-disease, excess physical or sexual activity, prolonged exposure to cold, or social factors such as interrupted access to medical care, food, medications, or heating oil. Identification of these risk factors might permit implementation of public-health measures directed at high-risk individuals. Although we are not certain whether persons with pre-existing heart-disease accounted for the increase in deaths observed in this study, snowstorms may precipitate angina in this group, and such people should be warned about the risks of exposure to cold and overexertion. Medical services should plan for more I.H.D. patients in the high-risk periods associated with blizzards.
W., Logue, R. B., Walter, P. F. in The Heart (edited by J. W. Hurst); p. 1175. New York, 1978. 2. Freedberg, A. S., Spiegl, E. D., Riseman, J. E. F. Am. Heart J. 1944, 27, 1. Hurst, J.
611.
Epstein, S. E., Stampfer, M., Beiser, G. S., Goldstein, R. E., Braunwald, E. New Engl. J. Med. 1969, 280, 7. 4. Hattenhauer, M., Neill, W. A. Circulation, 1975, 51, 1053. 5. Rogot, E., Fabsitz, R., Feinleib, M. Am. J. Epidem. 1976, 103, 198. 6. Rosenwaike, I. J. Am. stat. Ass. 1966, 61, 706. 7. Kutschenreuter, P. H. Trans N.Y. Acad. Sci. 1959, 22, 126. 8. Rogot, E. Publ. Hlth Rep. 1974, 89, 330. 9. Center for Disease Control. Reported Morbidity and Mortality in the United States. DHEW/USPHS/CDC Atlanta (5 volumes), 1973, 22, 47; 1974, 23, 48; 1975, 24, 50; 1976, 25, 54; 1977, 26, 62. 10. Armitage, P. Statistical Methods in Medical Research; Oxford, 1977. 11. Burgess, A. M. Rhode Island med. J. 1965, 68, 131. 12. Atlanta Constitution. Nov. 18, 1978, p. 3B. 13. Heggtveit, H. A. Am. Heart J. 1965, 69, 287. 3.
14.
H. C., Knowles, B. A. Urban Snow Hazard in the United States: A Research Assessment. U.S. Department of Commerce, June, 1975 PB
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