Depression: cost-of-illness studies in the international literature, a review.

BACKGROUND: Depression is one of the most ancient and common diseases of the human race and its burden on society is really impressive. This stems both from the epidemiological spread (lifetime prevalence rate, up to 30 years of age, was estimated as greater than 14.4% by Angst et al.) and from the economic burden on healthcare systems and society, but also as it pertains to patient well-being. AIMS OF THE STUDY: The scope of this review was to examine studies published in the international literature to describe and compare the social costs of depression in various countries. METHODS: A bibliographic search was performed on international medical literature databases (Medline, Embase), where all studies published after 1970 were selected. Studies were carefully evaluated and only those that provided cost data were included in the comparative analysis; this latter phase was conducted using a newly developed evaluation chart. RESULTS: 10 abstracts were firstly selected; 46 of them underwent a subsequent full paper reading, thus providing seven papers, which were the subject of the in-depth comparative analysis: three studies investigated the cost of depression in the USA, three studies in the UK and one study was related to Italy. All the studies examined highlight the relevant economic burden of depression; in 1990, including both direct and indirect costs, it accounted for US$ 43.7 billion in the US (US$ 65 billion, at 1998 prices) according to Greenberg and colleagues, whilst direct costs accounted for £417 million in the UK (or US$ 962.5 million, at 1998 prices), according to Kind and Sorensen. Within direct costs, the major cost driver was indeed hospitalization, which represented something in between 43 and 75% of the average per patient cost; conversely, drug cost accounted for only 2% to 11% in five out of seven studies. DISCUSSION: Indeed, our review suggests that at the direct cost level, in both the United States and the United Kingdom, the burden of depression is remarkable, and this is confirmed by a recent report issued by the Pharmaceutical Research and Manufacturers Association (PhRMA) where prevalence and cost of disease were compared for several major chronic diseases, including Alzheimer, asthma, cancer, depression, osteoporosis, hypertension, schizophrenia and others: in this comparison, depression is one of the most significant diseases, ranked third by prevalence and sixth in terms of economic burden. Moreover, in terms of the average cost per patient, depression imposes a societal burden that is larger than other chronic conditions such as hypertension, rheumatoid arthritis, asthma and osteoporosis. The application of economic methods to the epidemiological and clinical field is a relatively recent development, as evidenced by the finding that, out of the seven studies examined, three refer to the US environment, three to the UK and one to Italy, while nothing was available about the cost of depression for large countries such as France, Germany, Spain, Japan and others. IMPLICATION FOR HEALTH CARE PROVISION AND USE: The high incidence of hospitalization, and the finding that drug cost represents only a minor component of the total direct cost of the disease, suggests that room is still available for disease management strategies that, while effectively managing the patient's clinical profile, could also improve health economic efficiency. IMPLICATION FOR HEALTH POLICIES: Disease management strategies, with particular emphasis on education, should be targeted not only at patients and medical professionals but also at health decision makers in order "to encourage effective prevention and treatment of depressive illness". IMPLICATIONS FOR FURTHER RESEARCH: Cost of illness studies are a very useful tool allowing cost data comparisons across countries and diseases: for this reason, we suggest that further research is needed especially in some western European countries to assess the true economic burden of depression on societies.