Prescription medication use by Canadians aged 6 to 79
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Michelle Rotermann, Claudia Sanmartin, Deirdre Hennessy and Michele Arthur
Prescription medications are the second most costly component of health care, accounting for almost 14% ($29 billion) of Canada’s annual health care spending in 2013.Note1 This largely reflects pharmacological management of chronic diseases and conditions (for instance, heart disease and high cholesterol,Note2 hypertension,Note3 diabetesNote4 and depressionNote5) and pregnancy prevention.Note6
Despite the pervasive use of prescription medications, few national data sources are capable of supporting research. Some have restricted generalizibilityNote7; others are not population-based.Note7,Note8 The socio-demographic information in administrative dispensary or billing databases is also limited.Note7-9 Survey data, too, are problematic—most national surveys with prescription medication content are outdated or restricted to medications with specific indications.Note10-12
This analysis uses results from the combined 2007 to 2009 and 2009 to 2011 Canadian Health Measures Survey (CHMS) to estimate the prevalence of prescription medication use, profile medication users, and identify the most common prescription medication classes used by the household population aged 6 to 79 (see The data).
Prescription medication use
According to results of the 2007 to 2011 CHMS, 41% of community-dwelling 6- to 79-year-olds had taken at least one prescription medication within two days of their household interview (Table 1). This was lower than the 48% who reported to the 2007-2008 National Health and Nutrition Examination Survey (NHANES) in the United StatesNote13 that they had used prescription medication in the past month. Also, unlike the American data, the CHMS estimate excludes people aged 80 or older, a group known to be heavier users of medication.
Prescription drug use was also associated with the presence of physical and mental health conditions. Nearly all respondents who had four or more of the chronic conditions examined in this analysis reported taking prescription drugs in the past two days. Among people with at least three chronic conditions, the percentages were more than 90%; for those with none of the selected conditions, the figure was 22%. Similarly, the percentage of people reporting prescription medication use rose with increasing levels of disability and pain, and with lower levels of self-perceived health and emotional well-being.
The percentage of Canadians taking prescription drugs did not differ by household income. This is contrary to some other studies, which found that individuals at either income extreme tend to use more medications,Note21 or that medication use was inversely related to family income,Note20 material deprivation,Note22 and insurance status.Note19
Females were generally more likely than males to report taking prescription medications (47% versus 34%). However, at ages 6 to 14, a higher percentage of boys than girls used prescription medications, and at ages 65 to 79, the prevalence of prescription drug use was similar for men and women.
Women’s gynecological and reproductive health needs, in addition to differences in illness and health-seeking behaviour, likely account for the difference in prescription drug use by sex. Studies of health care service utilization in general have also frequently found higher use by women during the adult reproductive years, followed by a period of more balanced use, and higher use by men in later life.Note23
Prescription drug use intensity—the number of different medications taken—was strongly associated with age. The percentage taking more than one medication rose from 3% at ages 6 to 14 to 70% at ages 65 to 79 (Table 2).
Consistent with other Canadian estimates,Note12,Note24 polypharmacy—taking at least five prescription medications concurrently—was highest at approximately 30% among 65- to 79-year-olds. At ages 45 to 64, 11% used five or more prescription medications. Polypharmacy was rare—1.5% or less—among children and younger adults.
Although concurrent use of several prescription medications can increase the risk of adverse drug events, especially among seniors,Note25,Note26 multiple medication use can be difficult to avoid, as drugs taken to treat one condition may induce or worsen other conditions, a situation that, in turn, can necessitate additional medications.Note3,Note27,Note28
Leading drug classes
The leading prescription medications used by children and young adults (ages 6 to 24) were for attention deficit and hyperactivity disorder (ADHD) (males), depression, and contraception (females) (Table 3, Appendix). At ages 6 to 14, adrenergic inhalants, typically taken to manage asthma, were also common.
Among 25- to 79-year-olds, the leading prescription medication classes were lipid-lowering agents, ACE-inhibitors, peptic-ulcer and acid-reducers, beta-blockers (men), other analgesics and anti-pyretics (men) , anti-depressants (women), and thyroid medication (women) (Table 4, Appendix).
Because illnesses and other indications for medications vary over the life course, so do the leading medication classes. This is especially the case for women whose drug use up to age 45 is dominated by contraceptives, and then gives way to drugs such as estrogens, a type of hormone replacement therapy. Treatment of symptoms and risk factors associated with cardiovascular disease drives a considerable part of men’s medication use. Additionally, for men, the use of “other analgesics and anti-pyretics,” typically to treat pain and stiffness, was common. For both sexes, anti-depressants use peaked at ages 45 to 64 (17% among women and 8% among men).
Comparisons with analyses based on administrative data, such as the National Prescription Drug Utilization Information System database or province-specific estimates, and with American research show similarities in the most frequently used and/or most expensive drug classes, including medication for asthma, ADHD and anti-depressants among children and young adults, and cholesterol-lowering drugs, blood pressure medication, analgesics, beta-blockers and anti-depressants among older adults.Note8,Note19,Note29-31
This is the first national, population-based study to provide detailed information about current prescription drug use among community-dwelling Canadians aged 6 to 79. Prescription medications are widely used by the household population, and polypharmacy is common. As might be expected, distinct patterns of prescription medication use emerge by age and sex, and generally reflect physical and mental health status, as well as women’s gynecological and reproductive health needs. Leading medication classes for youth and adults were largely consistent with other Canadian and American research. As additional waves of CHMS data become available, it will be possible to combine successive cycles for more detailed investigation of prescription drug use in Canada.