The impact of prescription opioids on all-cause mortality in Canada
© The Author(s). 2016
Received: 19 April 2016
Accepted: 14 July 2016
Published: 1 August 2016
An influential study from the United States generated considerable discussion and debate. This study documented rising morbidity and mortality in midlife among white non-Hispanic Americans in the 21st century, with clear linkages of all-cause mortality to increasing rates of poisonings, suicides and chronic liver disease deaths. All of these causes of deaths are strongly related to the use of legal and illegal substances, but the study stressed the importance of prescription opioids. Given the similarities between the United States and Canada in prescription opioid use, the assessment of similar all-cause mortality trends is relevant for Canada. As this commentary highlights, the all-cause mortality shifts seen in the United States cannot be seen in Canada for either sex or age groups. The exact reasons for the differences between the two countries are not clear, but it is important for public health to further explore this question.
One of the most influential studies in public health in the United States (US) in 2015 highlighted a reversal of all-cause mortality decreases in midlife among white non-Hispanic Americans in the 21st century . This study triggered numerous newspaper reports, as well as debate [2–4]. It showed a clear link of all-cause mortality in this group to increasing rates of poisoning, suicide and chronic liver disease deaths, all of which are strongly related to use of legal and illegal substances . The non-medical use of prescription opioids (POs) was especially stressed in the study as the underlying risk factor for the all-cause mortality increases . Poisoning deaths related to POs, often referred to as overdose deaths, have been strongly linked to the overall level of PO use, with a near perfect correlation of 0.99 .
The study described above by Case and Deaton (2015) raises the question about similar all-cause mortality trends in Canada. Canada is second to the US in overall use of POs , but while the US has decreased their level of per capita use for the first time, Canada again increased it. Moreover, non-medical use of POs is relatively similar between the two countries. For example, non-medical use of POs reached 7.7 % in 2010 for Ontario , whereas the analogous estimate in the US was 5.5 % . It should be noted, however, that non-medical use of POs’ prevalence vary in both countries, with variability strongly associated with exact phrasing of relevant questions. Regarding other substance use, alcohol consumption per capita is higher in Canada than the US (10.2 L ethanol vs. 9.2 L ethanol) , whereas past 12-month cocaine use is lower (1.3 % vs. 2.2 %) , as is lifetime heroin use (0.5 % vs. 1.8 %) [12, 13]. Although the corresponding 12-month heroin use estimate is not available for Canada, there is no reason to believe that it would be higher than that observed for the US.
Case and Deaton (2015) included Canada in their comparisons with the US midlife age group (45–54 years), and found no such increase in all-cause mortality for the midlife age group in Canada, but rather a decrease. The present commentary extended similar assessments to other age groups as well. Based on the World Health Organization Mortality Database and World Population Prospects Database [14, 15], all-cause mortality rates were calculated by sex and 10-year age-groups. Changes in all-cause mortality rates were thereafter calculated for each successive decade from 1990 until 2011. Apart from changes in all-cause mortality rates, Pearson’s product moment correlations were computed between all-cause mortality rates and drug poisoning mortality rates (ICD-10 X40-X44, X60-X64, X85 and Y10-Y14) by sex from 2000 to 2011. All mortality rates were standardized according to the Canadian population in 1990.
All-cause mortality rates for males from 1990–2011 in Canada
Deaths per 100,000
All-cause mortality rates for females from 1990–2011 in Canada
Deaths per 100,000
The real decreases in all-cause mortality rates should be higher, given that the average age within the age groups has been increasing (for the effect in the US see ) . This latter effect is likely also responsible for the one exception in trends among the oldest females during the first decade of observation.
It should also be noted that although the drug poisoning mortality rates increased between 2000 and 2011 in Canada, these increases were considerably lower compared with those observed in the US. For example, drug poisoning mortality rates for those 45–54 years rose by 7 deaths per 100,000 and 6 deaths per 100,000 in Canada for males and females, respectively. The analogous increases in the US surmounted to 14 deaths per 100,000 for males and 16 deaths per 100,000 for females. Given the similarities in the use of legal and illegal substances between the two countries, the observed differences in these trends are noteworthy, but the exact reasons underlying these differences are not well understood.
In sum, the upward all-cause mortality shifts seen in the US cannot be seen in Canada for either sex or age groups, even though Canada has also been experiencing increases in PO use, non-medical use of POs and related overdose deaths [17, 18]. The exact reasons for the differences between the two countries are not clear, but it is important for public health to further explore this question.
PO, Prescription opioid; US, United States
The authors wish to thank Michelle Tortolo for referencing the manuscript.
Availability of data and materials
The datasets supporting the conclusions of this article are available from the World Health Organization [http://www.who.int/healthinfo/mortality_data/en/] and United Nations [http://esa.un.org/unpd/wpp/].
Authors SI and JR designed the study; SI and JR managed the literature searches and summaries of previous work; SI undertook the statistical analyses; SI wrote the first draft of the manuscript; JR edited the first draft of the manuscript; both authors have contributed to and have approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Not applicable, as all data was aggregated and publically available from the internet.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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