Social differences associated with the use of psychotropic drugs among men and women aged 65 to 74 years living in the community: the international mobility in aging study (IMIAS)

Our data come from the International Mobility in Aging Study’s (IMIAS) baseline data.
IMIAS is a longitudinal, multicentre, and multidisciplinary study focusing on five
cities: Kingston (Ontario, Canada), Saint-Hyacinthe (Quebec, Canada), Tirana (Albania),
Manizales (Colombia), and Natal (Brazil).

The study population consists of persons between the ages of 65 and 74 years residing
and living in the community. The sample was stratified by sex, and the aim was to
recruit 200 men and 200 women at each site. The overall sample size across the five
research sites was 1,995 persons. The data were collected in 2012.

In Tirana, Manizales, and Natal, participants were recruited from primary healthcare
community centres. At these sites, a random sample of elderly persons registered at
the health centre was selected, and participants were contacted directly by our investigators
with an invitation to participate in the study. All neighbourhood health centres in
Manizales, five neighbourhood health centres serving middle- and low-income populations
in Natal, and two neighbourhood health centres in Tirana serving middle-class populations
participated in the study. In Kingston and Saint-Hyacinthe, potential participants,
randomly chosen from the list of patients registered at the participating clinics,
received a letter from their family doctor inviting them to contact our field coordinator
to set up an appointment for a home visit 16]. In Saint-Hyacinthe, all patients came from the largest family medicine group clinic,
with which more than 80 % of physicians are affiliated and which covers the whole
territory of the city. In Kingston, the two clinics included in the study are large,
covering the whole Central Kingston area. In Saint-Hyacinthe the sample was stratified
by neighbourhood, while in Kingston this stratification was not possible. These indirect
methods of recruitment in the Canadian cities were required because the ethics committees
for the Canadian sites (Queens University and the University of Montreal) did not
authorize researchers to communicate directly with potential participants to invite
them to participate in a study. The response rate was around 95 % in Tirana, Manizales,
and Natal, and around 30 % in Kingston and Saint-Hyacinthe, where 95 % of the potential
participants who indicated interest by calling our research coordinator actually participated.

Participants who made four or more errors on the Leganes cognitive test (LCT), a screening
test for dementia, were excluded from the interview stage 17]. The data were collected at participants’ homes by trained investigators. An interview
was conducted, followed by anthropometric and blood pressure measures, as well as
tests of mobility and cognitive function, all administered in the appropriate language
(English, French, Albanian, Spanish, or Portuguese). The participants were asked whether
they had taken any prescribed or over-the-counter medications in the past two weeks.
If the answer was positive, the interviewer asked participants to show them all medical
drug containers and recorded the drug names.

Dependent variables

The data on psychotropic drug use were collected by identifying which of the drugs
used by participants during the period covered by the study were psychotropic (analgesic,
antiepileptic, antiparkinsonian, anxiolytic, sedative, hypnotic, or antidepressant).
Identification was based on the Anatomical Therapeutic Chemical (ATC) classification
system recommended by the WHO 18]. For analysis purposes, we grouped psychotropic drug use into four categories corresponding
to four dependent variables: 1) AEP – analgesic, antiepileptic, and/or antiparkinsonian
drugs (coded N02, N03, or N04); 2) ASH – anxiolytic and/or sedative/hypnotic drugs
(coded N05B or N05C); 3) ADP – antidepressant drugs (coded N06A); and 4) MSN, representing
use of at least one psychotropic drug (any drug coded N).

Independent variables

Socioeconomic status was measured using education, income, and occupation indicators.

Education level was self-declared, in answer to the question, “What is the highest
level of schooling you have completed?” The answers were grouped into two categories:
‘less than secondary school’ (for participants who had little education and had not
completed secondary school) and ‘secondary and above’ (for those having completed
secondary school or above).

Annual income was determined by asking study subjects, “What is your annual income
before taxes?” In Canada, annual income was considered low when it was less than $20,001
(Canadian dollars), medium when it was between $20,001 and $40,000, and high when
it was more than $40,000. Less than 20,000$ corresponds approximately to “Old Age
Security pension” in Canada for a single individual (17,000$) or a surviving spouse
(23,000$) 19]. For Latin America and Albania, low income corresponded to an annual income of $5,000
or less, medium income to an annual income from $5,001 to $10,000, and high income
to an annual income greater than $10,000. These cut-off points were based on the value
of old age pension in Brazil, which is around $360/month. For analysis, we created
two categories: low and medium incomes in one, high income in the other.

Occupation was established by asking the question, “What is the profession or occupation
you practiced for the majority of your life?” Occupations were classified according
to the International Labour Office’s 20] International Standard Classification of Occupations (ISCO-08), which distinguishes
among 10 occupational groups. For our study, these groups were split into two categories:
‘Non-manual occupation’ refers to managers and professionals in domains such as science,
engineering, health, teaching, or clerical office work; ‘manual occupation’ refers
to manual labourers, agricultural, services, and sales workers, craft and related
trade workers, housewives, and other basic occupations.

Potential covariates

Age, sex, and site of residence were collected. For purposes of comparing frequencies
of drug use, the Saint-Hyacinthe and Kingston sites were collectively identified as
Canadian sites, while Manizales and Natal were identified as Latin American sites.

Depression and the number of chronic illnesses were taken into account, both to measure
health needs and as possible confounding variables. Depression was identified using
a screening tool for states of emotional functioning, the Center for Epidemiologic
Studies Depression Scale (CES-D) 21]. A score 16 indicated the absence of elevated depressive symptomology, while a score
?16 indicated the presence of elevated symptomology possibly representing depression.

Chronic illnesses taken into account in this study were high blood pressure, diabetes,
chronic pulmonary diseases (chronic bronchitis, emphysema, asthma), heart diseases
(angina pectoris, heart failure), stroke, and chronic joint damage. For each one,
participants were asked whether a health worker had ever told them that they had the
illness. Responses were grouped into three categories according to the number of chronic
illnesses reported: zero to one, two to three, and four or more.

Statistical analyses

The proportions of psychotropic drug users were compared using bivariate analyses
based on socioeconomic and demographic factors. We conducted sex-specific analyses
to document social differences in psychotropic drug use in men and in women separately.
The frequencies of users of anxiolytics, sedatives, and hypnotics, of antidepressants,
of analgesics/antiepileptics/antiparkinsonians, and of at least one psychotropic drug
were compared through bivariate analysis using chi-square tests. As the use of psychotropic
drugs is a generally frequent phenomenon (more frequent than 10 %) and as we were
seeking a direct estimation of the prevalence ratio (PR), we adjusted the Poisson
regression with a robust variance correction 22]. Given the similarities between the distributions of Kingston and Saint-Hyacinthe
on the one hand and those of Natal and Manizales on the other, we pooled the data
of the Canadian cities and of the Latin American cities to increase precision of the
estimates in multivariate analysis.

The analyses were conducted using version 19 of the Statistical Package for the Social
Sciences (SPSS 19). For all tests, the significance threshold was 0.05.

Ethical considerations

The IMIAS study was approved by the research ethics committees of the University of
Caldas (Colombia), the Universidade Federal do Rio Grande do Norte (Brazil), the Albanian
Institute of Public Health (Albania), Queens University (Canada), and the University
of Montreal Hospital Research Centre (Canada). Written informed consent was obtained
from all subjects before their participation.