Liver Cirrhosis Mortality and Per Capita Alcohol Consumption in CanadaAuthor(s): Yang Mao, Howard Morrison, Roger J. Johnson and Robert SemenciwSource: Canadian Journal of Public Health / Revue Canadienne de Sante'e Publique, Vol. 83, No.1 (JANUARY / FEBRUARY 1992), pp. 80-81Published by: Canadian Public Health AssociationStable URL: http://www.jstor.org/stable/41990735 .

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Liver Cirrhosis Mortality and Per

Capita Alcohol Consumption in

Canada

Yang Mao, Ph.D.,1 Howard Morrison, Ph.D.,1

Roger /. Johnson, M.D., M.H.Sc.,2 Robert Semenciw, M.Sc.1

The association between per capita con- sumption of alcohol and liver cirrhosis morbidity and mortality has been well- documented both internationally1"8 and in Canada,9"12 but does not differentiate alco- holic from non-alcoholic cirrhosis.

METHODS

Liver cirrhosis mortality data were retrieved from the Canadian Centre for Health In- formation of Statistics Canada. Non-alcoholic cirrhosis records were extracted by selecting ICD-7 rubrics 581.0 and 298.0; ICD-8 ru- brics 571.8 and 571.9; and ICD-9 rubrics 571.4, 571.5, 571.6, 571.8 and 571.9. Al- coholic cirrhosis records were retrieved by selecting ICD-7 rubric 581.1, ICD-8 rubric 57 1 .0 and ICD-9 rubrics 57 1 .0, 57 1 . 1 , 57 1 .2 and 571.3.

Canadian per capita alcohol consumption between 1958 and 1986 was estimated from information derived from Liquor Control Boards and the Brewers Association of Canada for persons aged 15 years or older.13,14 The absolute alcohol content by volume was as- sumed to be 5%, 1 2% and 40% for beer, wine and spirits, respectively.

Age-standardized mortality rates (ASMRs) for alcoholic cirrhosis of the liver (ACL) and non-alcoholic cirrhosis of the liver (NACL) were calculated by the direct method using the 1971 Canadian population as a standard for the period 1958-1987. The association be- tween per capita alcohol consumption and

1 . Bureau of Chronic Disease Epidemiology, Labora- tory Centre for Disease Control, Department of National Health and Welfare

2. Medical Services Branch, Department of National Health and Welfare.

Address all correspondence and reprint requests to: Dr. Yang Mao, Cancer Division, Bureau of Chronic Disease Epidemiology, Laboratory Centre for Disease Control, Ottawa, Ontario K1A 0L2

age-standardized mortality rates for ACL, NACL and total cirrhosis of the liver was assessed by Pearson's correlation coefficients, using the data for 1958-1986.

RESULTS

ASMRs for ACL peaked during the period 1975-1977, whereas ASMRs for NACL peaked in 1974 (Figure 1). Between 1958 and 1973, NACL accounted for a greater proportion of liver cirrhosis deaths than ACL. However, since the mid-1970s, deaths from

NACL and ACL have been approximately equal in number.

The per capita consumption of absolute alcohol among Canadian adults increased steadily from 7.1 litres in 1958 to plateau at just over 1 1 litres from 1975 to 1981. Since 1981, there has been a steady decline. The correlation coefficient between annual per capita consumption of alcohol and liver cir- rhosis mortality was 0.88 (p<0.001), whereas the correlation between mortality from ACL and alcohol consumption was 0.97 (p<0.00 1 ) . More specifically, the correlation between

Figurei. Liver Cirrhosis Age-Standardized Mortality Rates* (ASMRs) per 100,000 and per capita alcohol consumption, Canada

80 REVUE CANADIENNE DE SANTÉ PUBLIQUE VOLUME 83, NO. 1

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LIVER CIRRHOSIS MORTALITY AND PER CAPITA ALCOHOL CONSUMPTION IN CANADA

mortality from ACL and the consumption of beer, spirits and wine was 0.96, 0.97 and 0.79 respectively (all pcO.OOl). The correlation between mortality from NACL and alcohol consumption was only 0.28 (p = 0.14). The correlation between NACL and alcohol fell from 0.83 (p<0.0001) during the first half of the study period (1958-1972) to 0.25 (p = 0.40) during the last half (1973-1986).

DISCUSSION

The strong correlation observed between ACL mortality and per capita consumption of alcohol supports the hypothesis that mortality from ACL is directly related to the level of alcohol consumption in the general population. This hypothesis is further sup- ported by a) the lack of a significant association between alcohol consumption and mortality from NACL, and b) the higher correlation found between alcohol consumption and ACL than between alcohol consumption and liver cirrhosis in general.

Several limitations were inherent in our data. Misclassification may have arisen from diagnostic error. The definitive diagnosis of alcoholic versus non-alcoholic liver cirrhosis is usually made by either a liver biopsy or at autopsy. Since neither procedure is routinely performed, some diagnostic error is inevitable.

A more important form of misclassification may have occurred because cases of alcoholic cirrhosis were labelled as non-alcoholic. It is presumably for this reason that alcoholic and non-alcoholic cirrhosis have not been sepa- rated in previous analyses. Over the 30-year span covered by this study, there have been major changes in Canada regarding how

alcoholism is perceived. With the change towards viewing alcoholism as a disease, the social stigma of alcoholism has diminished. This, combined with changes in physicians' awareness of alcoholism, may have increased the probability over the last 30 years that alcoholic cirrhosis was correctly diagnosed, and recorded on the death certificate. Evi- dence of this can be seen from the falling correlation over time between non-alcoholic cirrhosis and alcohol consumption.

The ASMR for NACL peaked in the mid- 1970s for males, at which time alcohol con- sumption was at its highest. Some of the increase in NACL may reflect increasing numbers of deaths from ACL, some of which were misclassified as NACL. However, an increase in alcohol consumption would have an adverse effect on a cirrhotic liver, regard- less of the etiology of the cirrhosis. Further- more, it is possible that some non-alcoholic cirrhotics also have an underlying problem with alcohol abuse and that an increase in consumption would further exacerbate their condition.

A limitation in our data is that per capita consumption of alcohol is a crude indicator of alcohol consumption. As well, population rates of liver cirrhosis mortality and alcohol consumption were examined without regard for the influence of possible confounders such as nutrition or socioeconomic status on liver cirrhosis mortality.

Although this paper has focused on the association between alcohol consumption and liver disease, decreases in mortality from cirrhosis of the liver may also be due to factors such as more effective medical therapy, and earlier recognition of alcohol abuse, resulting

in initiation of therapy prior to the onset of irreversible liver damage.

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Received: July 26, 1991 Accepted: August 3, 1991

JANUARY - FEBRUARY 1992 CANADIAN JOURNAL OF PUBLIC HEALTH 81

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