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Past and present socioeconomic circumstances and psychotropic medication: a register-linkage study
  1. Elina Mauramo1,
  2. Tea Lallukka1,
  3. Mikko Laaksonen1,
  4. Pekka Martikainen2,
  5. Ossi Rahkonen1,
  6. Eero Lahelma1
  1. 1Department of Public Health, Hjelt Institute, University of Helsinki, Helsinki, Finland
  2. 2Department of Social Research, University of Helsinki, Helsinki, Finland
  1. Correspondence to Dr Tea Lallukka, Department of Public Health, Hjelt Institute, University of Helsinki, P.O. Box 41, FIN-00014 Helsinki, Finland; tea.lallukka{at}helsinki.fi

Abstract

Background Various domains of socioeconomic circumstances are associated with self-reported mental health, but we lack evidence from studies using medically confirmed mental health outcomes. This longitudinal study aimed to examine the associations of multiple domains of socioeconomic circumstances with subsequent prescribed psychotropic medication among Finnish public sector employees.

Methods Baseline survey data among 40–60-year-old employees of City of Helsinki were linked with Social Insurance Institution of Finland register data on psychotropic medication purchases (n=5563). HRs were calculated using Cox regression to examine associations of parental and own education, childhood and current economic difficulties, occupational class, household income and housing tenure with antidepressants, sleeping pills and sedatives and any psychotropic medication during a 5-year follow-up.

Results In age and previous psychotropic medication adjusted models, the risk of antidepressant medication was higher in those with childhood (women: HR=1.29, men: HR=1.64) and current economic difficulties (women: HR=1.30–1.54), rented housing (women: HR=1.20, men: HR=1.45) and the second lowest income group (men: HR=1.71). Gradual adjustments had little effect on the associations. For sleeping pills and sedatives, similar associations were found in women for current economic difficulties, and in men for housing tenure. Results for any psychotropic medication reflected those observed for antidepressants.

Conclusions Past and present economic difficulties and housing tenure were more important determinants of subsequent psychotropic medication among employees than the conventional socioeconomic determinants. The associations were somewhat inconsistent between the medication groups and the sexes. The results support the importance of examining multiple domains of socioeconomic circumstances simultaneously.

  • Socioeconomic
  • social inequalities
  • social epidemiology
  • health behaviour
  • occupational health
  • sickness absence
  • mortality
  • ageing
  • registers
  • marital status
  • medical sociology FQ
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Introduction

It has been widely documented that disadvantaged socioeconomic circumstances are associated with a higher level of mental disorders. This is particularly the case for severe mental disorders, such as major depression.1–5 However, more varying results have been obtained for common mental disorders, that is, minor non-psychotic mental disorders, with negligible or even reverse associations having been found.6–9 Socioeconomic variation in psychotropic medication has also differed between studies, although there is a tendency for particularly antidepressant medication to be more prevalent in higher socioeconomic positions.10–14

One reason for the heterogeneity of the results has been the varying socioeconomic measures used and the lack of a comprehensive approach considering socioeconomic circumstances as a multidomain construct. Different indicators are not interchangeable but reflect different domains of socioeconomic circumstances and may produce differing associations with mental health outcomes.15 ,16 Among the conventional indicators, that is, education, occupational class and income, education primarily indicates non-material resources such as knowledge and skills, while occupational class reflects work-related status and working conditions. Education contributes to achieve occupational class and through this to income.17 Income, wealth and other domains of financial situation such as economic difficulties primarily indicate material resources and can affect mental health outcomes through behaviours and living conditions.18 ,19 Childhood circumstances may influence adult mental health directly or indirectly through other socioeconomic circumstances across the lifecourse.20 ,21

When multiple domains of socioeconomic circumstances have been simultaneously studied, material circumstances and economic difficulties have in many cases been particularly important for mental health, especially for common mental disorders, more so than education and occupational class.9 ,22–26 However, previous studies investigating several domains of socioeconomic circumstances have typically relied on cross-sectional data and self-reports of mental health. To be able to confirm how different domains of socioeconomic circumstances are associated with mental health, objective and medically confirmed outcomes, such as psychotropic medication, would be beneficial and help avoid limitations related to self-reports.

This study aimed to contribute to the understanding of the production of socioeconomic differences in mental health by examining the associations of socioeconomic circumstances with prescribed psychotropic medication in a multidomain socioeconomic framework. More specifically, associations of several past and present socioeconomic circumstances with different types of psychotropic medication over a 5-year follow-up were examined among middle-aged employees of the City of Helsinki, Finland. The study aimed to find out how the different domains of socioeconomic circumstances are associated with psychotropic medication and whether any pathways exist between the domains. The study examined the associations in different medication groups, that is, (1) antidepressants, (2) sleeping pills and sedatives and (3) any psychotropic medication.

Methods

Survey and register data

The data were derived from the Helsinki Health Study baseline postal surveys linked with 5-year follow-up register data from the Social Insurance Institution of Finland. The baseline surveys were conducted in 2000–2002 (N=8960, 67% responded). Each year, a questionnaire was posted to the employees of the City of Helsinki reaching the age of 40, 45, 50 and 60. The City of Helsinki is the largest employer in Finland, the employees representing several hundreds of occupations in mainly social and healthcare, education, public transportation, cultural services, environmental and technical maintenance and public administration.

The Social Insurance Institution register data include all purchases of prescribed reimbursed medication in Finland. The purchases were classified according to the Anatomical Therapeutic Chemical classification system.27 Three groupings of psychotropic medication were used: (1) antidepressants (Anatomical Therapeutic Chemical code N06A); (2) sleeping pills and sedatives (N05B and N05C); these mainly consist of benzodiazepine derivates and are used to induce sleep and reduce irritability or agitation; and (3) any psychotropic medication (N05 and N06 except medication for dementia N06D). Linkages were made using the unique personal identification numbers for those providing written consent for data linkages (74%, n=6606). Thus, participants with informed written consent to link their baseline survey responses with the register data on psychotropic medication were included in our study. Further drop off was due to item non-response on socioeconomic indicators and other variables used in the analyses. The number of participants analysed was 5563 (78% women), consisting of those who were free of psychotropic medication at the time of the baseline survey (319 current users excluded) and with information on all the variables needed. Psychotropic medication in 3 years preceding baseline was adjusted for as a covariate to show the associations between socioeconomic circumstances and subsequent psychotropic medication independent of previous medication. The Helsinki Health Study has been approved by ethical committees at the Department of Public Health, University of Helsinki, and at the City of Helsinki health authorities.

Socioeconomic measures

Seven domains of socioeconomic circumstances were measured. Parental education was based on either mother's and father's education: the higher one was chosen. Three groups were formed: higher, that is, matriculation or college examination or higher; intermediate, that is, secondary school or vocational training; and basic education, that is, primary school or lower. Childhood economic difficulties were measured by asking whether the respondent's childhood family had faced serious financial problems before the respondent's age 16, response categories being ‘yes’ and ‘no’. Own education was divided into three levels: higher, that is, university degree; intermediate, that is, matriculation or college examination; and basic, that is, secondary or vocational school. Occupational class was divided into four hierarchical categories: managerial and professional, semiprofessional, non-manual employees and manual workers. Household income was based on total household income during a typical month and equalised and weighted according to the modified Organisation for Economic Cooperation and Development (OECD) equivalence scale: the respondent received the value of 1.0, other adults 0.5 and children 0.3. Four hierarchical income groups were formed. Housing tenure was dichotomised into owner-occupiers and renters. Current economic difficulties were measured with two questions: ‘How much difficulties do you have in meeting the payment of bills?’ and ‘How often do you have enough money to buy the food or clothing you or your family need?’. A combined variable was categorised into ‘no difficulties’, ‘occasional difficulties’ and ‘frequent difficulties’.

Statistical methods

Cox regression analysis was used to examine the associations of the socioeconomic circumstances with psychotropic medication. Hazard ratios (HRs) and their 95% Confidence intervals (95% CIs) for the first event of purchasing medication during a 5-year follow-up were calculated. Schoenfeld residuals were used to test that the proportional hazard assumptions were met for all the variables. Psychotropic medication in 3 years preceding baseline was adjusted for. The socioeconomic circumstances were added in the regression models in an assumed temporal order. First, age-adjusted models including also previous medication were fitted. Next, childhood circumstances, that is, parental education and childhood economic difficulties were added. After that, conventional socioeconomic circumstances, that is, education, occupational class and household income were adjusted for. Finally, housing tenure and current economic difficulties were added in the full model. The analyses were conducted separately for women and men due to differences in medication over follow-up. The three psychotropic medication groups were also analysed separately.

Results

Prevalence of psychotropic medication

Among women, 16% had antidepressant medication, 12% sleeping pill and sedative medication and 24% any psychotropic medication during the 5-year follow-up (table 1). Among men, these figures were 11%, 9% and 17%, respectively. The incidence of antidepressant medication was higher among participants with childhood economic difficulties, in the non-manual occupational class and among renters. Also participants with current economic difficulties, particularly among women, had a higher incidence of antidepressants. Variations were smaller for sleeping pills and sedatives, with non-manual men and women with frequent current economic difficulties showing the highest incidence. Variations in any psychotropic medication largely resembled those of antidepressants, with women and men with childhood economic difficulties and rented housing, men in non-manual occupational class and women with current economic difficulties having the highest incidence.

Table 1

Number of participants (N) and prevalence (%) of psychotropic medication during a 5-year follow-up by socioeconomic circumstances, women and men

Socioeconomic circumstances and antidepressants

Among women, the age and previous psychotropic medication adjusted analyses showed no association with antidepressant medication for parental education, but an association for childhood economic difficulties (HR=1.29, 95% CI 1.08 to 1.54) was observed (table 2). Women with intermediate (HR=1.22, 95% CI 1.00 to 1.50) and basic education (HR=1.20, 95% CI 0.98 to 1.46) had a higher risk of antidepressant medication, while for occupational class and household income, associations were not observed. Also women with rented housing (HR=1.20, 95% CI 1.02 to 1.40) and occasional (HR=1.30, 95% CI 1.11 to 1.53) and frequent (HR=1.54, 95% CI 1.20 to 1.97) current economic difficulties had a higher risk. Adjustments mostly reduced the associations slightly, but the risks observed for intermediate (HR=1.32, 95% CI 1.01 to 1.72) and basic (HR=1.37, 95% CI 0.99 to 1.90) education somewhat increased when occupational class and income were adjusted for. After adjusting for education and income, a reverse association emerged for occupational class, manual workers (HR=0.57, 95% CI 0.38 to 0.84) being less likely to have antidepressant medication than higher classes. Otherwise, no clear pathways were found.

Table 2

Associations of socioeconomic circumstances with antidepressant medication during a follow-up of 5 years

Among men, age and previous psychotropic medication adjusted models showed no associations with antidepressant medication for parental education, while an association was observed for childhood economic difficulties (HR=1.64, 95% CI 1.11 to 2.43) (table 2). For education, no association was found. Non-manual employees (HR=1.51, 95% CI 0.94 to 2.41) and the second lowest income group (HR=1.71, 95% CI 1.05 to 2.76) were more likely to have antidepressants than those in other occupational classes and income groups. Housing tenure was associated with antidepressant medication, with renters being in higher risk (HR=1.45, 95% CI 1.03 to 2.04), but current economic difficulties were not associated with antidepressant medication. After adjustments, a higher risk of medication remained for childhood economic difficulties (HR=1.77, 95% CI 1.18 to 2.64), the second lowest income group (HR=1.80, 95% CI 1.09 to 2.97) and rented housing (HR=1.45, 95% CI 1.00 to 2.09). No clear pathways between the socioeconomic circumstances were found.

Socioeconomic circumstances and sleeping pills and sedatives

Adjusted for age, women with lower parental education had a lower risk of sleeping pill and sedative medication (HR=0.79, 95% CI 0.64 to 0.97) (table 3). Childhood economic difficulties, education, occupational class, income and housing tenure were not associated with sleeping pill and sedative medication, whereas women with frequent current economic difficulties showed a higher risk of medication (HR=1.30, 95% CI 0.98 to 1.72). The adjustments had little effect on the associations.

Table 3

Associations of socioeconomic circumstances with sleeping pill or sedative medication during a follow-up of 5 years

Among men, parental education, childhood economic difficulties, education, occupational class and income were not associated with sleeping pills and sedatives (table 3). Men with rented housing had a higher risk of sleeping pill and sedative medication in age and previous psychotropic medication adjusted (HR=1.78, 95% CI 1.21 to 2.63) and fully adjusted (HR=1.99, 95% CI 1.31 to 3.04) models. Men with intermediate parental education (HR=0.55, 95% CI 0.32 to 0.96) and frequent current economic difficulties (HR=0.32, 95% CI 0.11 to 0.94) had a lower risk of sleeping pill and sedative medication in the fully adjusted model. Overall, adjustments had little effect on the associations.

Socioeconomic circumstances and any psychotropic medication

Among women, parental education, childhood economic difficulties, education, occupational class and income were not associated with any psychotropic medication in age and previous psychotropic medication adjusted models (table 4). Women with rented housing (HR=1.17, 95% CI 1.03 to 1.34) and current economic difficulties (HR=1.15, 95% CI 1.01 to 1.31 and HR=1.26, 95% CI 1.02 to 1.56) had a higher risk of any psychotropic medication. Adjustments reduced the risk slightly. After the adjustments, a reverse association emerged for occupational class, manual workers being less likely to have any medication (HR=0.68, 95% CI 0.49 to 0.93) than higher classes.

Table 4

Associations of socioeconomic circumstances with any psychotropic medication during a follow-up of 5 years

Among men, childhood economic difficulties (HR=1.45, 95% CI 1.03 to 2.03) were associated with any psychotropic medication, while parental education was not. No association was observed for education. Non-manual employees (HR=1.50, 95% CI 0.99 to 2.25) and the second lowest income group (HR=1.49, 95% CI 1.00 to 2.23) were in age and previous psychotropic medication adjusted models more likely to have any psychotropic medication than other occupational classes and income groups. Men with rented housing (HR=1.73, 95% CI 1.30 to 2.32) had a higher risk, but for current economic difficulties, no association was found. Adjustments reduced the associations observed for occupational class and income, but those for childhood economic difficulties and housing tenure were unaffected.

Discussion

Main findings

This study examined associations of past and present socioeconomic circumstances with different types of psychotropic medication among municipal employees from Finland over a 5-year follow-up. The aim was to add our understanding of the production of socioeconomic differences in mental health with a multidimensional socioeconomic framework. We thus examined how different domains of socioeconomic circumstances are associated with psychotropic medication and whether any pathways between the domains could be found. Childhood economic difficulties in both sexes, as well as housing tenure among men and current economic difficulties among women, showed clearest associations with psychotropic medication, mainly antidepressants, while associations for conventional socioeconomic circumstances, that is, education, occupational class and income, were more inconsistent.

The first main finding was that past and current economic difficulties were associated with psychotropic medication. A moderate association was found for childhood economic difficulties and antidepressant medication among both sexes. For current economic difficulties, there was an association among women with antidepressants. The found associations are in line with what we have previously observed of childhood and current economic difficulties with self-reported common mental disorders measured by the General Health Questionnaire.25 ,26 Other longitudinal and cross-sectional studies using self-reported mental health outcomes have also documented associations between current economic difficulties and common mental disorders.21 ,23 ,28 Evidence from studies examining psychotropic medication or other medically confirmed mental health outcomes is scarce regarding economic difficulties other than, for example, unemployment-related poverty.29 For childhood economic difficulties, less previous evidence exists. However, studies have shown various kinds of childhood economic and other adversities to be associated with adult mental disorders.21 ,29–32 Childhood conditions have been suggested to influence adult health directly or indirectly through different factors and circumstances or by leading to accumulation of disadvantage throughout the lifecourse.20 ,21 However, in this study, the associations of childhood economic difficulties with antidepressant medication were independent of current circumstances, that is, no pathways between past and present were found.

Potential explanations for the associations between current economic difficulties and mental disorders may include material and also perceived deprivation, financial uncertainty and social relationships-related factors, which can act as acute or chronic exposures and stressors.21 ,33 ,34 These kinds of explanations might apply at least to some degree also to psychotropic medication even if some disparity may exist between the distribution of mental disorders and the related medication. The association between current economic difficulties and mental disorders found among women was not affected by adjustment for income, which suggests that mental health-affecting economic difficulties may arise due to other reasons than actual poverty, such as excess consumption and debt, which might further relate to general lifestyles, one's control over life or personality characteristics.24 ,35 We have previously found in the current cohort that associations of economic difficulties with self-reported mental disorders (General Health Questionnaire-12) were not explained by example health behaviours.26 Also in this study, the effects of alcohol consumption and physical activity were assessed but found to have negligible impact on the association between economic difficulties and psychotropic medication (data not shown). Overall, the explanations for this association, and the lack of the same association among men, remain open.

The second main finding was that those living in rented housing had psychotropic medication more commonly than owner-occupiers. This was observed for antidepressants among both sexes and for sleeping pills and sedatives among men. Renters have been shown to have poorer mental and physical health and higher mortality than owner-occupiers,36–38 but evidence on psychotropic medication is scarce. Housing tenure is assumed to reflect wealth and general material standards of living and thus affect health through pathways of deprivation-related factors. However, renters have been documented to have higher mortality regardless of income, occupational class or education.38 Therefore, renting-related health risks cannot be confined only to lacking overall financial assets as such. Other studies have suggested that, particularly in societies with a high percentage of owner-occupied housing, such as Finland, housing tenure also reflects housing quality and area characteristics, which may predispose to further health risks and influences.36

The third main finding was that the associations of conventional socioeconomic circumstances with psychotropic medication were inconsistent. However, the intermediate education class among women and intermediate occupational class (non-manual employees, mainly working in social and healthcare sectors) and income groups among men were somewhat more likely to have antidepressants. In earlier studies on common mental disorders, we have observed these domains of socioeconomic circumstances to show less consistent associations than economic difficulties.25 ,26 Other studies on self-reported common mental disorders have also shown negligible or even slightly reverse associations for these domains of socioeconomic circumstances,5 ,6 but for more severe mental disorders, positive linear associations have been found.2 ,3 However, when studying medication or hospital treatment, inconsistent associations could be even more likely because of the possibility of bidirectional effects of socioeconomic position, that is, individuals in lower positions having a higher risk of mental disorders but simultaneously being less likely to receive treatment than those in higher positions.39 Thus, because socioeconomic circumstances may influence the initiation and progress of the treatment process, it is possible that socioeconomic circumstances are somewhat differently associated with psychotropic medication treatment than with diagnosed mental disorders among the population. In Finland, antidepressant treatment has been more common among men in higher educational and occupational classes.10 In the USA, lower socioeconomic position has been associated with a lower quality of care for depressive and anxiety disorders.14 Other studies have also found that people with disadvantaged socioeconomic circumstances receive treatment less often.12–14 However, among the Finnish general population, no clear socioeconomic differences in the overall use of mental healthcare were found.40

Methodological considerations

An advantage of this study was its longitudinal design. Another major advantage was the use of complete national register data for the reimbursed prescribed psychotropic medication that could be linked with the baseline data. First, these increase the reliability and validity of the study. Also, the direction of associations can be reliably determined supporting causal interpretations, although limitations may still exist due to mental disorders often being longer-term problems. To minimise the possibility of health-related selection having an effect on the associations, we excluded individuals who at baseline had psychotropic medication. We also adjusted for psychotropic medication within 3 years preceding baseline.

However, there are also limitations to be considered. First, psychotropic medication is not a direct measure of medically confirmed mental disorders of various degrees. The measure is based on prescribed medication, which has led to purchases. Antidepressants and other psychotropics are sometimes also used for other than mental conditions such as chronic pain and insomnia. Factors such as comorbidity, which may be socioeconomically patterned, can affect the process of seeking and receiving medical treatment for depression or anxiety. Also, it should be noted that co-occurrence of the conditions treated by psychotropic medication is likely to be present. In the current data, 37% of those who had antidepressant medication during the follow-up had also purchased sleeping pills, hypnotics or sedatives, and 48% of those having sleeping pills had also purchased antidepressants. Second, the socioeconomic measures were based on self-reported survey information, except occupational class that was based partly (80%) on registers. Thus, problems generally associated with self-report apply also to this study. Responses concerning socioeconomic circumstances might be influenced with factors such as health or a disposition to respond negatively in surveys. Particularly responses to questions on economic difficulties and retrospective questions about childhood conditions might be affected. Third, it should be noted that the current results obtained in a cohort of municipal employees cannot directly be generalised into general populations, as both the prevalence of medication as well as the socioeconomic patterning could differ. The prevalence of psychotropic medication over the follow-up in the current study, that is, 11%–16% for antidepressants and 9%–12% for sleeping pills and sedatives, was slightly higher than what has been observed elsewhere for employees in Finland (9%–13% for antidepressants),10 and for example, Denmark (7% for antidepressants),41 which may be related to the characteristics of the population studied. Finally, we acknowledge that non-response at baseline and consent giving are potential sources of bias. However, our non-response analyses suggest that the data are broadly representative of the target population, and the associations between socioeconomic position and health are unlikely to be strongly biased due to non-participation.42 ,43 Men, younger participants, manual employees and those with long sickness absence spells were slightly over-represented among the non-respondents. Our further analyses of non-response suggest that age, occupational class and self-certified and medically certified sickness absence spells are broadly similar between the respondents and the non-respondents, and between those consenting and not consenting to register linkages.44

Conclusions

Living in rented housing and childhood economic difficulties in both sexes and current economic difficulties in women were associated with having psychotropic medication over the follow-up among middle-aged employees. In contrast, associations observed for education, occupational class and income were less consistent, with mainly intermediate groups having the highest risk of medication. Associations were mainly observed for antidepressants and less for sleeping pills and sedatives, whereas the combined group of any psychotropic medication largely reflected antidepressants, the most common type of medication.

Material circumstances such as housing tenure and everyday economic difficulties may thus be important socioeconomic determinants of psychotropic medication and medically confirmed mental disorders alongside the conventional domains of socioeconomic circumstances at least among employed populations. These domains of socioeconomic circumstances should thus also be considered in studies as a part of multiple socioeconomic circumstances. These results also underline the importance of supporting employees with economic disadvantages in order to prevent mental disorders and promote their mental health. Overall, in this study, different socioeconomic indicators produced different results and had little effect on each other's associations with psychotropic medication. This highlights the necessity of examining multiple domains of socioeconomic circumstances simultaneously instead of only one or two indicators to obtain a more complete understanding of the socioeconomic patterning of health.

What is already known on this subject

  • Various past and present socioeconomic circumstances have been widely documented to be associated with self-reported mental health.

  • Studies simultaneously examining multiple socioeconomic circumstances and medically confirmed mental health outcomes have been lacking.

What this study adds

  • Childhood and current economic difficulties and living in rental housing may be important risk factors of poor mental health and consequent psychotropic medication.

  • Material circumstances like these should be considered alongside the conventional socioeconomic circumstances, that is, education, occupational class and income, in both research and attempts to reduce mental health inequalities.

References

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Footnotes

  • Funding This study has been supported by Yrjö Jahnsson Foundation, the Finnish Work Environment Fund number 106065, and the Academy of Finland numbers 1121748, 1129225, 1135630, 133434 and 125733.

  • Competing interests None.

  • Ethics approval The Helsinki Health Study has been approved by ethical committees at the Department of Public Health, University of Helsinki, and at the City of Helsinki health authorities.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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