Assessing the worldwide epidemiology of sarcoidosis: challenges and future directions Yvette C. Cozier Affiliation: Slone Epidemiology Center at Boston University, Boston, MA, USA. Correspondence: Yvette C. Cozier, Slone Epidemiology Center at Boston University, 1010 Commonwealth Avenue, Boston, MA 02215, USA. E-mail: yvettec@bu.edu @ERSpublications Population-based studies reveal higher sarcoidosis morbidity and earlier mortality among males http://ow.ly/PcWr304uAKc Sarcoidosis is a chronic systemic disorder characterised by granulomatous inflammation targeted to an as-yet-unidentified antigen [1]. First described over 100 years ago by Caesar Boeck and others [2], sarcoidosis occurs worldwide and affects men and women of all ages and races [3–5]. The disease shows a consistent predilection for adults, with peak incidence occurring primarily before 40 years of age [3–6], although older age at onset has been widely reported [7–10]. Clinical presentation of sarcoidosis can be quite variable [11, 12], ranging from asymptomatic disease [3, 4], or acute onset with resolution [13, 14], while other patients experience chronic progressive illness affecting various organ systems and requiring systemic therapy [13–15]. Pulmonary disease affects the vast majority of diagnosed patients, but other organ systems are often affected as well [3, 4, 6]. Chronic progressive disease may require long-term treatment with corticosteroids, cytotoxics and other agents that have serious side-effects [3, 16, 17]. The lifetime risk of death is estimated to be between 1.0% and 7.6% [17, 18], with deaths attributed to respiratory, neurological or cardiovascular system involvement [19, 20]. While sarcoidosis is described worldwide and in all populations there is considerable disparity in the incidence, prevalence, and disease course between regions and populations. For example, the two groups reported to be most affected by the disease are African Americans and Northern Europeans [3, 21]. It has also been widely reported that sarcoidosis incidence is greater in women than in men [3–5], but the evidence is inconsistent. Data from the USA [22] and Sweden [7] have found similar rates between the two groups, while studies from Poland [23] and Denmark [8] reported higher incidence in men. A recent study in the USA reported higher incidence among women [24], while another study observed a higher prevalence of sarcoidosis for women than men in all racial/ethnic groups [9]. In the USA, sarcoidosis patients experience higher mortality and at younger ages [25, 26]; age-adjusted mortality rates are greater in females than males, and are consistently higher in black than white patients [25]. Accurate characterisation of sarcoidosis in varied populations is an important step towards formulating strategies for control and treatment of the illness. However, important gaps remain in our knowledge of the epidemiology and aetiology of the disease. These gaps are both highlighted and partially filled by two articles featured in the current issue of the European Respiratory Journal. The first, by ARKEMA et al. [27], estimates incidence and prevalence rates based on data from the Swedish National Patient Register, a comprehensive national database capturing sarcoidosis diagnoses over a 50-year period (1964–2013) among all Swedish residents aged ⩾18 years. The authors assessed disease frequency in the entire Swedish population by age, sex, education and geography. An important finding from their dataset was that 56% of prevalent cases and 55% of incident cases were male, and that the median age at diagnosis for men was nearly a decade younger than that of women (45 versus 54 years). The authors, however, downplay the Copyright ©ERS 2016 Received: Sept 15 2016 | Accepted: Sept 15 2016 Conflict of interest: None declared. Eur Respir J 2016; 48: 1545–1548 | DOI: 10.1183/13993003.01819-2016 1545 | EDITORIAL SARCOIDOSIS