Estimating cumulative point prevalence of rare diseases: analysis of the Orphanet database

International audienceAbstract Rare diseases, an emerging global public health priority, require an evidence-based estimate of the global point prevalence to inform public policy. We used the publicly available epidemiological data in the Orphanet database to calculate such a prevalence estimate. Overall, Orphanet contains information on 6172 unique rare diseases; 71.9% of which are genetic and 69.9% which are exclusively pediatric onset. Global point prevalence was calculated using rare disease prevalence data for predefined geographic regions from the ‘Orphanet Epidemiological file’ ( http://www.orphadata.org/cgi-bin/epidemio.html ). Of the 5304 diseases defined by point prevalence, 84.5% of those analysed have a point prevalence of <1/1 000 000. However 77.3–80.7% of the population burden of rare diseases is attributable to the 4.2% ( n = 149) diseases in the most common prevalence range (1–5 per 10 000). Consequently national definitions of ‘Rare Diseases’ (ranging from prevalence of 5 to 80 per 100 000) represent a variable number of rare disease patients despite sharing the majority of rare disease in their scope. Our analysis yields a conservative, evidence-based estimate for the population prevalence of rare diseases of 3.5–5.9%, which equates to 263–446 million persons affected globally at any point in time. This figure is derived from data from 67.6% of the prevalent rare diseases; using the European definition of 5 per 10 000; and excluding rare cancers, infectious diseases, and poisonings. Future registry research and the implementation of rare disease codification in healthcare systems will further refine the estimates

Cumulative incidence of SARS-CoV-2 infection within the homeless population: insights from a city-wide longitudinal study

Objectives The aim of this study was to determine the risk factors associated with SARS-CoV-2 infection in a cohort of homeless people using survival analysis. Seroprevalence in the homeless community was also compared with that of the general population.Design Cohort study.Setting Data were collected across two testing sessions, 3 months apart, during which each participant was tested for anti-SARS-CoV-2 antibodies and completed a face-to-face survey.Participants All homeless adults sleeping rough, in slums or squats, in emergency shelters or transitional accommodation in Marseille were eligible.Primary outcome measures Occurrence of a seroconversion event defined as a biologically confirmed SARS-CoV-2 infection. Local data from a national seroprevalence survey were used for comparison between homeless people and the general population.Results A total of 1249 people were included. SARS-CoV-2 seroprevalence increased from 6.0% (4.7–7.3) during the first session to 18.9% (16.0–21.7) during the second one, compared with 3.0% (1.9–4.2) and 6.5% (4.5–8.7) in the general population. Factors significantly associated with an increased risk of COVID-19 infection were: having stayed in emergency shelters (1.93 (1.18–3.15)), being an isolated parent (1.64 (1.07–2.52)) and having contact with more than 5–15 people per day (1.84 (1.27–2.67)). By contrast, smoking (0.46 (0.32–0.65)), having financial resources (0.70 (0.51–0.97)) and psychiatric or addictive comorbidities (0.52 (0.32–0.85)) were associated with a lower risk.Conclusion We confirm that homeless people have higher infection rates than the general population, with increased risk in emergency shelters. There is growing evidence that, in addition to usual preventive measures, public policies should pay attention to adapt the type of accommodation and overall approach of precariousness.Trial registration number NCT0440813