Davies, Newton, McNeill, Fisher, Kesson and Pearson
Metabolic control in diabetic subjects
when exclusions were included the total mortality rate in diabetic subjects was higher at 22%. This is still less than the Dundee retrospective controls at 42% and Gwilt et al's rate of 33%. This may reflect the general improved prognosis observed in patients on CCU's though in Dundee the mortality rate in non-diabetics apparently rose from the 14% observed by Clark et al to 17% during this study period. These variations are likely to reflect the relatively small numbers of patients studied. Despite using four centres, the rate of patient recruitment was such that we would have had to continue the study for a further 4-5 years to obtain 270 subjects. Thrombolytic therapy became available towards the end of the study but only seven patients received streptokinase (three in the infusion group only) and one of these died. Potassium balance was identical in all groups studied and mild hypokalaemia was observed in only two subjects who both remained uncomplicated. As well as suffering an increased incidence of ischaemic heart disease, diabetic patients continue to have a higher mortality rate and incidence of cardiac complications following myocardial infarction. Though intravenous insulin infusion is the preferred method of diabetic control in patients with compromised circulation or metabolic decompensation, adequate diabetic control may be achieved by
other methods.f though many physicians and CCU's find it simple and flexible to use an infusion regimen. To test whether an improvement in metabolic control will improve survival in diabetic patients suffering myocardial infarction will require more aggressive lowering of blood glucose levels than that achieved in this study. ACKNOWLEDGEMENTS: We wish to thank the Scottish Hospital Endowments Research Trust for financial support, the staff of the CCU's for their kind co-operation and Dr I. Ross for measuring Hb levels. REFERENCES 1 Oliver MF, Kurien VA, Greenwood TW. Relation between serum free fatty acids and arrhythmias and death after acute myocardial infarction. Lancet. 1968; i: 710-715. 2 Vik-Mo H, Mjos D. Influence of free fatty acids on myocardial oxygen consumption. Am J Cardiol, 1981; 48: 361-365. 3 Gwilt DJ, Petri M, Lamb P, Nattrass M, Pentecost BL. Effect of intravenous insulin infusion on mortality among diabetic patients after myocardial infarction. Br Heart J. 1984; 51; 626-630. 4 Clark RS, English M, McNeill GP, Newton RW. Effect of intravenous infusion of insulin in diabetics with myocardial infarction. Br Med J. 1985; 291: 303-305. 5 Hopper JL, Pathik B, Hunt D, Chan WWc. Improved prognosis since 1969 of myocardial infarction treated in a coronary care unit: lack of relation with changes in severity. Br Med J. 1989; 299: 892-8%. 6 Husband DJ, Alberti KGMM, Julian DG. Methods for the control of diabetes after acute myocardial infarction. Diabetes Care. 1985; 8: 261-267.
Scot Med J 1991; 36: 076-082
0036-9330/91/01091/076 $2.00 in USA © 1991 Scottish Medical Journal
COMPOSITION OF SEASONALITY OF DISEASE
A.S. Douglas, T.M. Allan, 1.M. Rawles University Department of Medicine and Therapeutics, Wellcome Library, Medical School, University of Aberdeen
Abstract: The composition of the seasonality of total death was ascertained. Vascular disease seasonality constitutes more than half The remaining seasonality is influenced by respiratory disease. Surprisingly and of possible importance cancer mortality was not seasonal. Deaths from 'all other disease' and from 'injuries' is seasonal. Seasonality increases with age. In coronary and cerebrovascular disease death has a large seasonal fluctuation. On the other hand hospital admissions and survivors have a minor seasonal fluctuation - only cerebrovascular admissions reaching the chosen level of significance with a small seasonal amplitude. For vascular disease the ranking of seasonal fluctuation from greatest to least is - death outside hospital, total death, death inside hospital, admissions, survivors. It is death outside hospital presumably 'sudden' that imposes seasonality on coronary disease in general. For respiratory diseases not only death but hospital admissions and survivors have high amplitude seasonality with a much greaterfluctuation than for death in vascular disease.
Keywords: Seasonality, death, disease, composition, vascular, coronary, cerebrovascular, respiratory. Introduction EASONALITY of total death is well known. J. Gaunt (1620-1674) reported mortality statistics in the City of London in his 'Natural and political observations made upon the Bills of Mortality' in 1662 but the first important data on seasonality was by Quetelet 1842. 1 There are many other important reference sources on seasonal fluctuations in total mortality. 2,3 This is the first time a study on season has been made
S
Correspondence and reprint requests: Professor A.S. Douglas, University Department of Medicine and Therapeutics, Medical School, Polwarth Building, University of Aberdeen, Foresterhill, Aberdeen AB9 2ZB.
incorporating record linkage on admissions and examination of total death in a defined geographical area. The investigation deals with the contribution to seasonality ofdeath (total, outside and inside hospital), admissions, survivors and the percentage of hospital death amongst admissions. The role of age is examined. In this first paper, only broad disease categories are explored. Others have dealt with death from individual diseases but no previous examination is known to us where the composition of seasonality of total death has been described. Material and Methods Figures for mortality and hospital admissions were
76
Downloaded from scm.sagepub.com at UNSW Library on July 25, 2015
Douglas, Allan and Rawles
Composition of seasonality of disease
obtained by month for the years 1974-1988 for Grampian; while having their own regional health authorities, the Orkney and Shetland figures are incorporated into Grampian. The population is half a million with four-fifths served by the Aberdeen hospitals. The remaining one-fifth is served by hospital development in Elgin and small hospitals in Orkney and Shetland. Mortality data was collected in the following ICD codes (9th revision). I-XVII - inclusive i.e. total death. II - Neoplasms 140-239(N). VII - Diseases of the Circulatory System 390-459. 410-414Ischaemic Heart Disease (IHD). 430-438Cerebrovascular Disease (CVD). Other Circulatory Disease. VIII - Respiratory Diseases (RD) 460-519. The remainder (I-XVII excluding II, VII, VIII) - all other diseases and deaths due to 'injury and poisoning XVII'. Because circulatory and respiratory disease contribute in a major way to seasonality of death, data on admissions for IHD 410-414, CVD 430-438 and RD 460-519 were examined for seasonality. Statistical methods
In order to test for seasonal vanation in the monthly data, cosinor analysis was used," in which the best fit of a cosine function curve to the annual data is determined. The year is considered as 360 degrees, and the midpoint of each month of the year is assigned an angular value, t, for January 15 degrees, February 45 degrees, through to December 345 degrees. Multiple regression analysis is performed between the monthly data and sin(t) and cos(t). From the analysis are obtained the multiple correlation coefficient R, its statistical significance, and the angular position in the year (converted to the nearest month) when the fitted sinusoidal regression line has its highest value; this is called amplitude in the text. In the analysis correction for month length was made to a 31 day month. Cosinor analysis is illustrated in Figure 1 upper, where the total mortality data is plotted from July to June (showing the 'mountain' of deaths in the winter months) and also from January-December. In Figure 1 upper the actual data are presented with the cosinor analysis mesor
July
Jan
Oct
April
June
10,000
120
9000
Metabolic control in diabetic subjects
when exclusions were included the total mortality rate in diabetic subjects was higher at 22%. This is still less than the Dundee retrospective controls at 42% and Gwilt et al's rate of 33%. This may reflect the general improved prognosis observed in patients on CCU's though in Dundee the mortality rate in non-diabetics apparently rose from the 14% observed by Clark et al to 17% during this study period. These variations are likely to reflect the relatively small numbers of patients studied. Despite using four centres, the rate of patient recruitment was such that we would have had to continue the study for a further 4-5 years to obtain 270 subjects. Thrombolytic therapy became available towards the end of the study but only seven patients received streptokinase (three in the infusion group only) and one of these died. Potassium balance was identical in all groups studied and mild hypokalaemia was observed in only two subjects who both remained uncomplicated. As well as suffering an increased incidence of ischaemic heart disease, diabetic patients continue to have a higher mortality rate and incidence of cardiac complications following myocardial infarction. Though intravenous insulin infusion is the preferred method of diabetic control in patients with compromised circulation or metabolic decompensation, adequate diabetic control may be achieved by
other methods.f though many physicians and CCU's find it simple and flexible to use an infusion regimen. To test whether an improvement in metabolic control will improve survival in diabetic patients suffering myocardial infarction will require more aggressive lowering of blood glucose levels than that achieved in this study. ACKNOWLEDGEMENTS: We wish to thank the Scottish Hospital Endowments Research Trust for financial support, the staff of the CCU's for their kind co-operation and Dr I. Ross for measuring Hb levels. REFERENCES 1 Oliver MF, Kurien VA, Greenwood TW. Relation between serum free fatty acids and arrhythmias and death after acute myocardial infarction. Lancet. 1968; i: 710-715. 2 Vik-Mo H, Mjos D. Influence of free fatty acids on myocardial oxygen consumption. Am J Cardiol, 1981; 48: 361-365. 3 Gwilt DJ, Petri M, Lamb P, Nattrass M, Pentecost BL. Effect of intravenous insulin infusion on mortality among diabetic patients after myocardial infarction. Br Heart J. 1984; 51; 626-630. 4 Clark RS, English M, McNeill GP, Newton RW. Effect of intravenous infusion of insulin in diabetics with myocardial infarction. Br Med J. 1985; 291: 303-305. 5 Hopper JL, Pathik B, Hunt D, Chan WWc. Improved prognosis since 1969 of myocardial infarction treated in a coronary care unit: lack of relation with changes in severity. Br Med J. 1989; 299: 892-8%. 6 Husband DJ, Alberti KGMM, Julian DG. Methods for the control of diabetes after acute myocardial infarction. Diabetes Care. 1985; 8: 261-267.
Scot Med J 1991; 36: 076-082
0036-9330/91/01091/076 $2.00 in USA © 1991 Scottish Medical Journal
COMPOSITION OF SEASONALITY OF DISEASE
A.S. Douglas, T.M. Allan, 1.M. Rawles University Department of Medicine and Therapeutics, Wellcome Library, Medical School, University of Aberdeen
Abstract: The composition of the seasonality of total death was ascertained. Vascular disease seasonality constitutes more than half The remaining seasonality is influenced by respiratory disease. Surprisingly and of possible importance cancer mortality was not seasonal. Deaths from 'all other disease' and from 'injuries' is seasonal. Seasonality increases with age. In coronary and cerebrovascular disease death has a large seasonal fluctuation. On the other hand hospital admissions and survivors have a minor seasonal fluctuation - only cerebrovascular admissions reaching the chosen level of significance with a small seasonal amplitude. For vascular disease the ranking of seasonal fluctuation from greatest to least is - death outside hospital, total death, death inside hospital, admissions, survivors. It is death outside hospital presumably 'sudden' that imposes seasonality on coronary disease in general. For respiratory diseases not only death but hospital admissions and survivors have high amplitude seasonality with a much greaterfluctuation than for death in vascular disease.
Keywords: Seasonality, death, disease, composition, vascular, coronary, cerebrovascular, respiratory. Introduction EASONALITY of total death is well known. J. Gaunt (1620-1674) reported mortality statistics in the City of London in his 'Natural and political observations made upon the Bills of Mortality' in 1662 but the first important data on seasonality was by Quetelet 1842. 1 There are many other important reference sources on seasonal fluctuations in total mortality. 2,3 This is the first time a study on season has been made
S
Correspondence and reprint requests: Professor A.S. Douglas, University Department of Medicine and Therapeutics, Medical School, Polwarth Building, University of Aberdeen, Foresterhill, Aberdeen AB9 2ZB.
incorporating record linkage on admissions and examination of total death in a defined geographical area. The investigation deals with the contribution to seasonality ofdeath (total, outside and inside hospital), admissions, survivors and the percentage of hospital death amongst admissions. The role of age is examined. In this first paper, only broad disease categories are explored. Others have dealt with death from individual diseases but no previous examination is known to us where the composition of seasonality of total death has been described. Material and Methods Figures for mortality and hospital admissions were
76
Downloaded from scm.sagepub.com at UNSW Library on July 25, 2015
Douglas, Allan and Rawles
Composition of seasonality of disease
obtained by month for the years 1974-1988 for Grampian; while having their own regional health authorities, the Orkney and Shetland figures are incorporated into Grampian. The population is half a million with four-fifths served by the Aberdeen hospitals. The remaining one-fifth is served by hospital development in Elgin and small hospitals in Orkney and Shetland. Mortality data was collected in the following ICD codes (9th revision). I-XVII - inclusive i.e. total death. II - Neoplasms 140-239(N). VII - Diseases of the Circulatory System 390-459. 410-414Ischaemic Heart Disease (IHD). 430-438Cerebrovascular Disease (CVD). Other Circulatory Disease. VIII - Respiratory Diseases (RD) 460-519. The remainder (I-XVII excluding II, VII, VIII) - all other diseases and deaths due to 'injury and poisoning XVII'. Because circulatory and respiratory disease contribute in a major way to seasonality of death, data on admissions for IHD 410-414, CVD 430-438 and RD 460-519 were examined for seasonality. Statistical methods
In order to test for seasonal vanation in the monthly data, cosinor analysis was used," in which the best fit of a cosine function curve to the annual data is determined. The year is considered as 360 degrees, and the midpoint of each month of the year is assigned an angular value, t, for January 15 degrees, February 45 degrees, through to December 345 degrees. Multiple regression analysis is performed between the monthly data and sin(t) and cos(t). From the analysis are obtained the multiple correlation coefficient R, its statistical significance, and the angular position in the year (converted to the nearest month) when the fitted sinusoidal regression line has its highest value; this is called amplitude in the text. In the analysis correction for month length was made to a 31 day month. Cosinor analysis is illustrated in Figure 1 upper, where the total mortality data is plotted from July to June (showing the 'mountain' of deaths in the winter months) and also from January-December. In Figure 1 upper the actual data are presented with the cosinor analysis mesor
July
Jan
Oct
April
June
10,000
120
9000
