Hospitalizations & Deaths

Ethics approval was obtained from the University of British Columbia, Behavioural Research Ethics Board (H06-04043). Mortality and hospital data were received from BC Vital Statistics and BC Ministry of Health (respectively) by age group, sex, health authority, health services delivery area (mortality only), and year. All data are securely held at BC Centre for Disease Control. The underlying cause of death code (UCOD) and the most responsible diagnosis code (MRD) were used in the computation of alcohol, tobacco, and illicit drug attributable mortality and morbidity respectively. All rates were standardized by age and sex using the 2001 BC population as the standard population.

Computing Alcohol-
Attributable Fractions

AFs for chronic diseases are calculated by using the formula:

AF= [Σ^k_i=1 P_i(RR_i–1)]/ Σ^k_i=0 P_i(RR_i–1) + 1

where,

k = total levels of exposure

i = exposure category with baseline exposure or no exposure i=0

RR(i) = relative risk at exposure level i compared to no consumption

P(i) = prevalence of the i^th category of exposure

Relative risk estimates were obtained from a meta-analysis of previous literature. Four levels of alcohol consumption were used: abstainer, low, hazard, and harmful. This corresponds to 2.5 grams of ethanol or less, 2.6-40, 41-60, and 61 or more grams of ethanol per day for men and 2.5 or less, 2.6-20, 21-40, and 41 or more grams per day for women. (One glass of beer or wine is equivalent to 15 grams of ethanol).Prevalence data were obtained from recent provincial and national surveys. For injuries attributable to alcohol, AFs were based on direct estimates of alcohol involvement from the published literature.

Alcohol AFs were then adjusted using BC consumption data. BC per capita consumption was taken from the alcohol consumption component of the BC AOD monitoring project. The data from this component, however, does not reflect unrecorded alcohol consumption. A further 10% was added to the BC per capita consumption data to account for unrecorded alcohol consumption. New alcohol AFs were then estimated using the following formula:

AF_x = ([F*AF_ref]+AF_ref ) / ([{F*AF_ref}+AF_ref]+[1-AF_ref])

where,

AF_x = estimated population alcohol aetiologic fraction for the population of interest

AF_ref = population aetiologic fraction for reference year

F = change factor in per capita consumption from reference year to year of interest

for

F = (PCC _ref - PCC_x) / (PCC _ref * -1)

where,

PCC _ref = per capita consumption for reference year (eg. Rehm et al. used 9.77 for 2002), and

PCC _x = per capita consumption for year of interest

Computing Tobacco-
Attributable Fractions

AFs were calculated using the formula above. Relative risk estimates and prevalence data were obtained from a meta-analysis of previous literature and recent provincial and national surveys respectively.

Computing Illicit Drug-
Attributable Fractions

For diseases that exist completely because of drug use, the AF is by definition 100%. For suicides, we took the number of suicides with illicit drugs as a contributing factor divided by the total number of suicides. For hepatitis C virus (HCV) and HIV, we used estimates from literature of the proportions of HCV- and HIV-positive individuals who are injection drug users. For low birth weight due to maternal opiate consumption, we used the formula above. For hepatitis B virus (HBV) and endocarditis, we used the AF from literature. For homicide and motor vehicle accidents (MVA), we used estimates of cannabis- and cocaine-caused MVA and homicides from literature.

AFs were then multiplied with overall mortality and hospitalization numbers to obtain the total burden of disease from alcohol, illicit drugs and tobacco by age, sex, and health authority.

Notes

For detailed prevalence and relative risk estimates, please see The Cost of Substance Abuse in Canada 2002 (Rehm J. et al. 2006).

This project uses the same ICD 10 tables for alcohol, tobacco and illicit drugs that were used in Jurgen Rehm’s project.

Permission to share these results was obtained from the BC Ministry of Health Data Steward and the BC Provincial Health Officer.

Dr. Jane Buxton MBBS, FRCPC
Associate Professor, School of Population and Public Health, UBC
Physician Epidemiologist, BC Centre for Disease Control

Dr. Buxton also chairs the BC provincial harm reduction strategies and service committee. Her research focus includes communicable disease control, outbreak investigation, hepatitis A, B and C, harm reduction, alcohol and illicit drug use epidemiology. Current research projects include youth injection prevention; and participatory research with women who have been released from prison; and hepatitis B vertical transmission. Awards and scholarships include BC Provincial Health Officer’s Award for Excellence in Public Health for commitment to knowledge generation and translation; commitment to teaching, research, and being Time magazine’s “Drug Warrior".

Mr. Andrew Tu
Research Assistant, BC Centre for Disease Control

Andrew is currently working at the BCCDC as a research assistant to Dr. Jane Buxton. He is responsible for creating the databases for the mortality and morbidity component of the monitoring system and analyzing the data. Andrew is currently studying towards a PhD in the School of Population and Public Health at UBC. His research topic is identifying BMI trajectories in adolescents from psychosocial factors. He is also interested in exploring psychosocial factors associated with eating behaviours.

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