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Short Report

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Unemployment and dispensed prescribed antidepressants in Stockholm County 1998–09 Andreas Lundin1, Anders Hansson2 1 Division of Occupational and Environmental Medicine, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden 2 Department of Statistics and Comparisons, National Board of Health and Welfare, Stockholm, Sweden Correspondence: Andreas Lundin, Division of Occupational and Environmental Medicine, Institute of Environmental Medicine, Karolinska Institutet, SE 17176, Stockholm, Sweden. e-mail: [email protected]

The association between unemployment rates and population mental health has been studied with contradictory results. We examine the association between unemployment and antidepressants in Stockholm County. Age- and sex-specific monthly data on unemployment and dispensed prescribed antidepressants from January 1998 to January 2008 in Stockholm County were used. The association was studied with bivariate cointegration analysis with stationarity check of the residuals. We found that dispensing of antidepressants was inversely associated with unemployment. One interpretation is that antidepressants have not followed decreasing unemployment rates.

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Introduction ndividual-level data consistently show worse mental health among

Ithe unemployed. The association between unemployment rates and

population mental health, studied through suicide rates, mental health service utilization and aggregated symptoms, show inconsistent evidence.1 In this study, we examine unemployment rates and dispensing of antidepressants, as antidepressants should be a good proxy of depression, which is accurately registered and is known to correlate (inversely) with suicide rates.2–4 It is also, unlike suicide, common enough to study using monthly intervals, and this lowerlevel statistics reduce the risk that associations are lost due to aggregation bias. The aim of this study is to analyse the association between unemployment and the dispensing of prescribed antidepressants in Stockholm County, Sweden, from January 1998 to January 2008.

Methods The study was performed on unemployment and dispensed antidepressants in Stockholm County (1.9 million inhabitants) using routinely monthly collected data on unemployment and dispensed

antidepressants between January 1998 and January 2008. Data on unemployment were obtained from the Swedish Public Employment Service. Data for monthly dispensed prescribed antidepressants were obtained from Stockholm County Council. All rates were per 100 000. Before 2009, the sole and exclusive right to retail medicine was held by the state-owned National Corporation of Swedish Pharmacies. Data include information on all prescriptions dispensed at local pharmacies to individuals registered as residing in Stockholm County in aggregate form. Drugs are classified according to the Anatomical Therapeutic Chemical (ATC) system, and utilization is defined in defined daily doses (DDDs). A DDD is defined as the assumed average maintenance dose per day for a drug used for its main indication in adults—a World Health Organization (WHO) unit intended to enable comparisons across time and between countries.5 We extracted monthly data on dispensed DDDs of prescribed antidepressants, ATC code N06A. Recipes are valid for 12 months.

Statistical analysis We studied the association between unemployment and antidepressants by testing the cointegration of the two monthly time series. In

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European Journal of Public Health, Vol. 24, No. 4, 666–668 ß The Author 2014. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved. doi:10.1093/eurpub/cku079

Unemployment and dispensed prescribed antidepressants

the first step, augmented Dickey–Fuller (ADF) test was used to examine the stationarity of the univariate time series.6 If the time series were stationary at level or after differencing, we used Engle and Granger7 two-step procedure to test for cointegration between the two series; antidepressants were first regressed on lags of unemployment; thereafter, we tested the stationarity of the obtained residuals with ADF. All statistical analyses were conducted in SAS 9.1.3 using PROC ARIMA. Analyses were restricted to 1998 and forward because a new reimbursement scheme for drug prescription in 1997 led to hoarding in 1996 followed by a general decline in dispensing in 1997.

Results

not follow an increase in unemployment. We used antidepressants as a proxy for depression, but our findings do not support the idea that unemployment is associated with increased prevalence of antidepressant users or increased overall level of dispensing. It might be, however, that individuals managing their illness using antidepressants respond to unemployment and/or the recession. Our findings are, of course, limited to Sweden, which might be of great importance. Earlier studies on aggregate and individual data have suggested that labour market programmes might be a modifying factor between unemployment and ill mental health.10 Labour market programmes are relatively generous and prescribed pharmaceutics subsidized so that no one ever has to pay more than SEK 1800 (168 EUR, January 2008) in any 12-month period.

Strength of the study The main strength of this study is its use of reliable data on unemployment and pharmacy dispensing data. All those who work in Sweden are entitled to financial unemployment benefits conditional on that you register with the Employment Service as being ‘fit and available to work for an employer at least 3 h/day and for an average of 17 h/week’ and ‘prepared to accept job offers of appropriate work’. The use of data obtained on prescribed and dispensed antidepressants at the sole legal provider offered complete data coverage on a proxy for mental ill health, an area where point prevalence is difficult to obtain.

Weakness of the study

Discussion In this study, monthly aggregate unemployment between January 1998 and January 2008 was inversely associated with monthly aggregate dispensed antidepressants during the same period. We know of no previous study on the specific association between aggregate unemployment and antidepressants, although studies on the association between antidepressants and suicide rates have hypothesized that unemployment rates might be a potential confounder because of its affiliation with suicide (for a review, see study by Ludwig et al.8). Although some time-series analysis on unemployment and ill mental health measures have found a positive association,9,10 others report no association.11,12 In one Danish individual-level study,13 unemployed were more likely to be prescribed antidepressants, but controlling for previous depressive symptoms, this association was almost completely explained indicating confounding.

Not everyone who is seeking work and fulfil the official criteria of being unemployed utilize the ‘Swedish Public Employment Service’. However, because registering at the ‘Swedish Public Employment Service’ is a requirement to be entitled to financial unemployment benefits from any of the unemployment insurance funds, which are in general practice, the greater majority of jobseekers without employment will have done so. There is also a strong agreement between registered unemployment and estimations based on official Labour Force Survey. Another limitation is that a change in DDDs does not have to correspond to a change in number of treated individuals. Lastly, this study was conducted in Stockholm County, a metropolitan area but with rural surroundings, and our findings might not be generalizable to other settings. Conflicts of interest: None declared.

Key points Explaining the findings At the centre of debate concerning unemployment and ill health is health-related selection, stating that if those who are prone to ill health simultaneously are also more likely to lose their jobs, then an association will arise between unemployment and ill mental health, which is not to be interpreted as unemployment causing the ill mental health. On an aggregate level, such bias does not occur—if there is no effect of unemployment on an individual’s risk of becoming depressed, then prevalence of depression does Table 1 Cointegration between unemployment and antidepressants. Regression coefficients and ADF unit root test results Sex and age Men 16–64 Women 16–64 Men 18–24 Women 18–24

a

a

B

SE

13.27 30.10 5.64 20.31

3.76 8.42 1.49 3.20

T

b

3.53 3.57 3.78 6.34

P

 When unemployment goes up, the prevalence of mental health sometimes follows.  This study shows a negative association between unemployment and dispensed prescribed antidepressants.

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Carlsten A, Waern M, Ekedahl A, Ranstam J. Antidepressant medication and suicide in Sweden. Pharmacoepidemiol Drug Saf 2001;10:525–30.

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WHO. Guidelines for ATC classification and DDD assignment. WHO Collaborating Centre for Drug Statistics Methodology, Guidelines for ATC classification and DDD assignment 2013, Oslo, (2012).

6

Dickey DA, Fuller WA. Likelihood ratio statistics for autoregressive time series with a unit root. Econometrica 1981;49:1057–72.

b

0.0006 0.0005 0.0002

Unemployment and dispensed prescribed antidepressants in Stockholm County 1998-09.

The association between unemployment rates and population mental health has been studied with contradictory results. We examine the association betwee...
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