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The epidemiology of psychiatric disorders among young people is a topic often discussed within the media. However, the reported prevalence of child and adolescent psychiatric disorders depends upon the sample studied, temporal context and methodology used. Within the UK, the use of large, methodologically rigorous surveys has improved understanding of disorders at a population level. The findings paint a solemn picture with 1 in 8 young people found to have a diagnosable mental disorder in 2017 and follow ups in 2020 and 2021 suggesting this may have increased to 1 in 6. The main drivers in these increases appear to be a rise in emotional disorders, particularly in older adolescents and most strikingly among females. Other disorders, when compared across timepoints, appear to have remained relatively stable in prevalence. The classification of disorders within child and adolescent psychiatry is also an ever-evolving field with changes made in each new diagnostic manual which reflect current thinking and the incorporation of new knowledge. This chapter discusses recent changes to the classifications of disorders in child and adolescent mental health and recent epidemiological findings.
Postpartum depressive symptoms (PPDS) are mental health concerns, characterised by sadness, anxiety and suicidal ideation.
Aims
We aimed to estimate the prevalence of PPDS, identify its associated factors and explore the lived experiences of individuals with PPDS, to understand the psychosocial mechanisms involved.
Method
We surveyed 400 women aged 18 years and above and conducted in-depth interviews among 19 women who screened positive for PPDS at two urban hospitals and one peri-urban polyclinic in Ho, Ghana. We used multivariable binomial generalised linear models to identify factors independently associated with PPDS. We used thematic analysis (qualitative) to identify themes that highlight pathways through which these factors influence PPDS.
Results
Overall, 117 (29.3%) women screened positive for PPDS. Being unmarried (adjusted prevalence ratio (aPR) 1.33, 95% CI 1.02–1.72), lack of partner support (aPR 1.60, 95% CI 1.21–2.12), history of depressive or psychiatric disorders (aPR 2.44, 95% CI 1.84–3.25), unplanned pregnancy (aPR 1.63, 95% CI 1.18–2.25), low self-esteem (aPR 2.38, 95% CI 1.79–3.16) and low birth weight (aPR 1.87, 95% CI 1.33–2.65) were independently associated with PPDS. The thematic analysis revealed four key themes: (a) social isolation and limited support, (b) emotional stress and vulnerability, (c) self-image and identity challenges, and (d) resilience resources.
Conclusions
PPDS were common in our sample and were significantly associated with modifiable factors such as prior mental health history and low self-esteem. These findings underscore the importance of prioritising maternal mental health through the integration of depression screening and psychosocial care into routine antenatal and postnatal services.
Improving udder health on dairy farms requires knowledge about the prevailing mastitis pathogens in order to take appropriate measures. The aim of this research communication was to evaluate the association between two sampling approaches for determining the prevalence of mastitis pathogens in dairy herds. Sampling approaches tested included (a) bacteriological investigation of randomly selected cows independent from stage of lactation (random sampling) and (b) sampling of cows two weeks prior to drying off (dry-off sampling). Using linear regression, the prevalence of mastitis pathogens were compared on herd-level for groups of specific pathogens. Associations between the prevalence estimated by the two approaches were found for Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus uberis and Gram-negative bacteria but not for other esculin-positive streptococci. This study indicated that both sampling approaches provide farmers with an overview of the prevalence of mastitis pathogens in their herds, with the dry-off results also being used to target antibiotic use to infected quarters.
Attaining the target of <0.1% HBsAg positives in children aged <5 years in vaccinated populations by 2030 is a WHO indicator of hepatitis B elimination. We aimed to calculate the prevalence of HBsAg- and anti-HBc-positive children and adolescents in the low-prevalence country of Germany. In total, 3567 children and adolescents aged 3–17 years participated in a national population based cross-sectional study. Data were collected between 2014 and 2017 using questionnaires and health examinations, including blood samples. Applying a weighted analysis to account for survey design and participant characteristics, we calculated the HBsAg and anti-HBc prevalence and described them by anti-HBs positivity. In total, 3007 participants had all three sero-markers measured. None were found HBsAg and anti-HBc positive. Seven (0.3%, 95% CI: 0.1–0.8) were anti-HBc positive and HBsAg negative; six were also anti-HBs positive. All anti-HBc-positive participants were aged ≥7 years and three had no migration background. Four anti-HBc-positive participants had known vaccination status; three had been vaccinated according to national recommendations. This very low hepatitis B virus sero-prevalence among children and adolescents indicates that Germany is reaching some hepatitis B virus elimination targets. We recommend maintaining preventive measures, in particular a high vaccination coverage, in order to reach hepatitis B elimination.
First-episode psychosis (FEP) is a critical phase in psychotic disorders where early intervention significantly influences long-term outcomes. Catatonia, characterised by motor, behavioural, and psychological abnormalities, is an under-recognised aspect of FEP.
Aims
This study examines catatonia prevalence in affective and non-affective FEP, its role as a severity indicator across psychopathological domains, its correlations with other symptoms and its association with clinical syndromes.
Method
A cross-sectional study was conducted with 58 FEP patients (38 females, 20 males) aged 15–55 years. Of those, 40 were antipsychotic-naive, and 18 had minimal prior antipsychotic exposure. Participants were recruited from acute psychiatric units. Catatonia was assessed using the Bush Francis Catatonia Rating Scale (BFCRS), while psychopathology was evaluated with the Positive and Negative Symptom Scale (PANSS), Calgary Depression Scale (CDS) and Young Mania Rating Scale (YMRS). Data analysis included descriptive statistics, t-tests, X2 tests, and multivariable regression using SPSS version 25 for Windows.
Results
Catatonic signs were identified in 22.4% of cases based on the Bush Francis Catatonia Screening Instrument (BFCSI) criteria (BFCSI-positive group, defined as ≥2 signs present for over 24 h), indicating potential catatonia. Prevalence varied by criteria: 13.8% (DSM-IV), 10.3% (Fink and Taylor), 10.38% (ICD-11) and 8.6% (DSM-5). Catatonic patients had more years of education and significantly higher PANSS totals, Emsley negative, disorganised, excited, and anxiety scores. Catatonic signs moderately correlated with Emsley disorganised scores. Regression analysis identified PANSS total and Emsley domain scores as significant predictors of catatonia severity.
Conclusions
Catatonia is notably prevalent in FEP and associated with severe psychopathology, particularly in negative and disorganised domains. These findings underscore the importance of improving recognition of catatonia in early psychosis. Larger longitudinal studies are needed to confirm these findings and explore treatment implications.
The medical profession is associated with high demands and occupational stressors – including confrontation with illness and death, extended work hours, and high workload – which may increase the risk of traumatization and posttraumatic stress disorder (PTSD). This systematic review aimed to synthesize evidence on prevalence of PTSD among physicians and examine potential moderators, including the COVID-19 pandemic, specialties, and geographic regions.
Methods
A systematic search was conducted in PubMed, Web of Science, PsychINFO, and PubPsych up to April 2025. Included studies were English-language, peer-reviewed, observational studies, reporting PTSD prevalence in physicians, using validated instruments. Studies focusing on preselected PTSD cases or mixed healthcare samples were excluded. Data extraction included study methodology, measurement tools, geographic region, specialty, and survey timing (pre-/“post”-COVID). Risk of bias was assessed using the JBI critical appraisal checklist for prevalence studies. Quantitative synthesis and moderator analyses were performed. The review was registered with PROSPERO (ID CRD42023401984).
Results
Based on 81 studies (N = 41,051), the pooled PTSD prevalence using a random-effects model was 14.9% (95% CI [0.132–0.168]). Prevalence estimates were lower in high-income (13.6%) compared to middle-income countries (21.1%) (p < 0.036). Studies employing brief screening tools (≤10 items) yielded significantly lower prevalence estimates (10.2%) than those using longer instruments (16.4%) (p < 0.027). No other significant moderators were identified.
Conclusion
PTSD prevalence among physicians is elevated relative to the general population, with notable variation across regions and measurement approaches. Future research should address gaps in representativeness and geographic coverage to improve prevalence estimates and guide prevention strategies.
The Diagnostic and Statistical Manual of Mental Disorders – 5th Edition (DSM-5) and International Classification of Diseases – 11th Revision (ICD-11) employ different post-traumatic stress disorder (PTSD) criteria, necessitating updated prevalence estimates. Most of the existing evidence is still based on ICD-Tenth Revision and DSM-Fourth Edition criteria, leading to varied estimates across populations. This study provides current PTSD prevalence rates in the German general population, comparing DSM-5 and ICD-11 criteria and examines variations by age and gender.
Methods
In a 2016 cross-sectional survey of 2404 adults (18–94 years) representative of the German general population, participants completed the Life-Events-Checklist for DSM-5 (LEC-5) for trauma exposure and the PTSD Checklist for DSM-5 (PCL-5) for PTSD symptoms. Probable PTSD diagnoses were based on DSM-5-, ICD-11-algorithms and suggested cut-off scores. Chi-square and McNemar’s tests were used to test differences in prevalence rates by diagnostic framework, age and gender.
Results
Of the total sample, 47.2% (n = 1135) reported experiencing at least one lifetime traumatic event (TE), with transportation accidents (7.3%) and life-threatening injuries (4.9%) being most common. Probable PTSD prevalence was 4.7% under both DSM-5 and ICD-11 criteria, and 2.6% based on a conservative cut-off normed for prevalence estimation. Gender and age were not significantly associated with TE exposure or PTSD prevalence, though trauma types varied: female participants more often reported sexual violence and severe suffering, while more male participants reported physical assaults and various types of accidents. DSM-5 and ICD-11 diagnostic algorithms had substantial yet not perfect agreement (κ = 0.62). Particularly within the re-experiencing symptoms, cluster agreement was only moderate (κ = 0.57). The cut-off method aligned more closely with DSM-5 (κ = 0.60) than ICD-11 algorithm (κ = 0.42).
Conclusions
This study provides updated PTSD prevalence estimates for the German general population and underscores differences between DSM-5 and ICD-11 in identifying cases, particularly with respect to re-experiencing symptoms. These findings emphasize that while overall PTSD prevalence rates under DSM-5 and ICD-11 criteria are similar, the diagnostic frameworks identify partially distinct cases, reflecting differences in symptom definitions. This highlights the need to carefully consider the impact of evolving diagnostic criteria when interpreting prevalence estimates and comparing results across studies.
This study aims to estimate the prevalence of human papillomavirus (HPV) infection and describe its genotype distribution in MSM in Hong Kong. In this longitudinal study on Chinese MSM, multi-anatomic site self-sampling and testing for HPV, Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) were performed following survey completion at baseline and one-year follow-up. Overall, 41% (288/701) of MSM completed self-sampled HPV testing. HPV positivity was 29% (78/270) and 33% (42/127) at any anatomic site at baseline and follow-up timepoints, respectively. By anatomic site, HPV positivity was 26%-30%, 2%-4% and 0%-1% from rectal, penile, and pharyngeal specimens, respectively. The incidence of HPV infection was 21.2/100 and 18.9/100 person-years at any anatomic site and rectal site, respectively. Among 109 successfully genotyped samples, the most prevalent were HPV 6 (17%) and HPV 11 (16%), of which 60% of the genotyped samples were vaccine-preventable. Group sex engagement and less frequent condom use were positively associated with HPV infection (P<0.05). The HPV prevalence and incidence in MSM in this study is lower than in Western countries, and low-risk HPV genotypes are more prevalent. The high proportion of vaccine-preventable HPV subtypes underscores the importance of HPV vaccination in preventing infections in MSM.
Risk factors for Eimeria infections are well documented in farm and pet animals, but studies focusing on wildlife species are less common. This research aimed to investigate the impact of selected demographic and environmental factors on the prevalence of Eimeria in the European hare (Lepus europaeus). Additionally, we analysed whether Eimeria infection affected the behaviour of hares by examining the relationship between infection status and the likelihood of a hare being killed by a vehicle at a hotspot for road mortality. Between 11 February 2022 and 24 June 2024, we collected 22 hare carcasses that had been killed in traffic along an 83.9 km monitoring route in central Bohemia, Czech Republic, to evaluate Eimeria prevalence in relation to factors such as age, hare density, distance to the nearest water source and rainfall over the previous 3 months. Contrary to our expectations, we found a higher prevalence of Eimeria in adult hares compared to juveniles. We propose that this outcome may be due to the high mortality rates among leverets and juvenile hares, which removes susceptible individuals from the population early on. The effects of the other factors examined were not significant. In conclusion, our study revealed that Eimeria infection did not contribute to the clustering of hare–vehicle collisions. We emphasize the importance of studying risk factors in wildlife species across different ecological contexts. Our findings challenge the general assumption that age negatively influences Eimeria prevalence.
Epidemiological studies on catatonia encounter several methodological challenges, and as a result, the historical epoch and clinical context must be carefully considered when estimating its incidence and prevalence. Over the past 70 years, the reported incidence and prevalence of catatonia have significantly declined, influenced by several key historical developments, including the widespread use of antipsychotic medications, shifts in diagnostic criteria, advances in psychiatric care, and changes in the clinical recognition of the disorder. The reclassification of catatonic symptoms as antipsychotic-induced motor side effects, along with the decentralization of psychiatric care and shorter patient observation periods, contributed to this decline. This chapter explores the limitations of epidemiological research on catatonia, particularly regarding its prevalence across diverse patient populations. It provides a detailed analysis of catatonia’s incidence and prevalence in different epochs, various clinical settings, considering factors such as sex ratios, age distribution, ethnicity, and recurrence rates, supported by the most recent scientific evidence.
Cross-cutting issues like nutrition have not been adequately addressed for children with severe visual impairment studying in integrated schools of Nepal. To support advocacy, this study aimed to determine the nutritional status of this vulnerable group, using a descriptive cross-sectional design involving 101 students aged 5–19 years from two integrated public schools near Kathmandu Valley and two in western Nepal. The weight-for-age z-score (WAZ), height-for-age z-score (HAZ), and body mass index-for-age z-score (BAZ) were computed and categorised using World Health Organization cut-off values (overnutrition: z-score > +2.0 standard deviations (SD), healthy weight: z-score −2.0SD to +2.0SD, moderate undernutrition: z-score ≥ −3.0SD to <−2.0SD, severe undernutrition: z-score < −3.0 SD) to assess nutritional status. A child was considered to have undernutrition for any z-scores <−2.0SD. Multivariate logistic regression was used to analyse variables linked to undernutrition. The mean age of participants was 11.86 ± 3.66 years, and the male-to-female ratio was nearly 2:1. Among the participants, 71.29% had blindness, and 28.71% had low vision. The mean BAZ and HAZ scores decreased with age. The WAZ, HAZ, and BAZ scores indicated that 6.46% were underweight, 20.79% were stunted, and 5.94% were thin, respectively. Overall, 23.76% of students had undernutrition and 7.92% had overnutrition. More than three in ten students had malnutrition and stunting was found to be prevalent. Older students and females were more likely to have undernutrition. These findings highlight the need for nutrition interventions within inclusive education settings, particularly targeting girls with visual impairments who may face compounded vulnerabilities.
Specific phobias are common in the community, and much is known from epidemiological surveys about their subtypes and sex ratio.
Aims
To determine the subtypes and sex ratio in a treatment-seeking sample of people with a specific phobia.
Method
Patients with a specific phobia were identified by a retrospective search of clinical case records from patient notes in electronic health records at the South London and Maudsley NHS Foundation Trust (the largest secondary mental healthcare provider in Europe).
Results
We identified 1017 patients over 5 years as having a specific phobia. The adult female to male sex frequency ratio for having any specific phobia was 3.9, with the ratio of specific phobia subtypes ranging from 2.4 (natural environment) to 8.2 (animal). The child female to male ratio of specific phobia subtypes ranged from 0.7 (natural environment) to 1.8 (other subtypes). Phobia of vomiting was the most common specific phobia presenting in both adults (n = 161, 17.8% of all specific phobias) and children (n = 26, 23.4%). In adults with a phobia of vomiting, the female to male ratio was 9.1 compared with 3.4 in all other specific phobias, and 4.2 versus 0.98 for children.
Conclusions
There is a stark contrast between the apparent prevalence of phobia of vomiting in epidemiological surveys and being the most common presentation clinically. A very high female to male ratio in phobia of vomiting and animals in adults seeking treatment is also in contrast to findings in the community. This has implications for clinician training and public education.
Fasciolosis, a parasitic disease of ruminants, poses significant economic and animal-health challenges in Algeria. This study aimed to assess spatial, temporal, and species-specific patterns of fasciolosis prevalence across diverse agro-climatic zones and to estimate associated economic losses. Between 2013 and 2023, eight wilayas El-Tarf, Skikda, Jijel (Region I), Blida, Mila (Region II), and M’Sila, Medea, Laghouat (Region III) were surveyed. Systematic postmortem inspections of 1,569,392 animals (349,176 cattle; 982,669 sheep; 235,639 goats; 1,882 camels; 26 horses) were performed by qualified veterinarians, with liver and bile-duct examination for Fasciola. Data on region, species, year, and season were analyzed in R 4.4.0 using ANOVA, Kruskal–Wallis, Tukey’s post hoc tests, and principal component analysis (PCA). Economic losses were calculated from condemned liver weights in Blida, Laghouat, and Jijel, converted to USD. PCA distinguished three regional prevalence profiles, with PC1 (77.7% variance) separating overall prevalence levels. Region I exhibited the highest mean prevalence (2.47%), peaking at 3.54% in 2018 – significantly greater than Region II (1.39%) and Region III (1.96%) (p < 0.01). Cattle showed the greatest infection rate (mean 4.14%), significantly higher than sheep (1.32%; p < 0.001) and goats (0.25%; p < 0.001), while horses and camels remained uninfected. Seasonal analysis revealed highest prevalence in autumn and winter (≈2.1%) versus spring (≈1.5%). Economic losses totaled USD 10.6 million in Blida, USD 1.0 million in Laghouat, and USD 142.2 million in Jijel over the study period. Targeted control strategies, adapted to regional and seasonal risk patterns, are essential. Future work should investigate environmental and management factors driving regional differences and evaluate cost-effective interventions to mitigate fasciolosis impact in Algerian livestock.
Data on the infection of Middendorffʼs eelpout, Hadropareia middendorffii, by metacercariae of the trematodes Cryptocotyle lingua Creplin, 1825 and Liliatrema skrjabini Gubanov, 1953, which are causative agents of black spot disease, is provided here for the first time for Taui Bay, Sea of Okhotsk. The prevalence of infection of fish by larvae of C. lingua reached 79%, while the intensity of infection varied from one to 278 individuals (with an average of 53). The prevalence of infection by L. skrjabini was lower (40%), with an intensity from one to 22 larvae (on average, eight). Metacercariae of both trematode species were surrounded by two envelopes: an outer, connective tissue capsule formed by the host’s cells, and an inner cyst formed by the parasite. The examined metacercariae were found in all regions of the fish’s body (head, trunk, and fins), with approximately equal numbers of individuals of both species found in tissues of the head and trunk regions. Metacercariae of C. lingua were localised in the fishes’ muscles, not only immediately under the skin but also in deeper layers. The capsules formed around metacercariae of both trematode species were dominated by fibroblasts and collagen fibres and did not show pronounced signs of inflammation. Studying the distribution of black spot disease and its effects on fish is crucial for understanding disease patterns in relation to fish population dynamics. It may also inform the development of effective anthelmintic treatments for use in aquaculture farms.
Population dynamics of aquatic parasites respond to factors like host availability, habitat age and quality. Amphipods are intermediate hosts for Acanthocephala, a widespread group of parasitic worms. Acanthocephalan infections of amphipods can easily be detected, and the widespread occurrence of amphipods makes their infection status an attractive potential proxy for the ecological status of their aquatic environment, including stressors introduced by urbanization. This study investigated the prevalence and the species-level and genetic diversity of Acanthocephala in the stream amphipod Gammarus fossarum. The study streams cross forested, agricultural and urban landscapes in the eastern foothills of the European Alps. Parasite prevalence ranged from 0% to 8.8% and increased towards downstream reaches independent of surrounding land use. Oxford Nanopore Technology was used to sequence the mitochondrial cytochrome oxidase I barcoding locus to identify parasite species and assess their genetic diversity. The majority of the parasites were Pomphorhynchus tereticollis, which use fish as definitive hosts. Despite their relative abundance in the studied streams, their genetic diversity was low and the most common haplotype was found at all sampling sites, which might indicate population expansion. Amphipods also hosted P. laevis and Polymorphus sp. type 1, the first evidence of this cryptic species within Polymorphus cf. minutus in Austria. Genetic diversity was high in Polymorphus sp. type 1, possibly reflecting a large effective population size due to gene flow maintained by the avian final hosts. The low and downstream-biased prevalence suggests that definitive hosts may be a limiting factor for Acanthocephala populations in small streams.
Accumulating evidence shows that an increasing number of children and young people (CYP) are reporting mental health problems.
Aims
To investigate emotional disorders (anxiety or depression) among CYP in England between 2004 and 2017, and to identify which disorders and demographic groups have experienced the greatest increase.
Method
Repeated cross-sectional, face-to-face study using data from the Mental Health of Children and Young People surveys conducted in 2004 and 2017, allowing use of nationally representative probability samples of CYP aged 5–16 years in England. A total of 13 561 CYP were included across both survey waves (6898 in 2004 and 6663 in 2017). We assessed the prevalence of any emotional, anxiety and depressive disorder assessed using the Development and Well-Being Assessment and classified according to ICD-10 criteria.
Results
The prevalence of emotional disorders increased from 3.9% in 2004 to 6.0% in 2017, a relative increase of 63% (relative ratio 1.63, 95% CI 1.38, 1.91). This was largely driven by anxiety disorders, which increased from 3.5 to 5.4% (relative ratio 1.63, 95% CI 1.37, 1.93). The largest relative changes were for panic disorder, separation anxiety, social phobia and post-traumatic stress disorder. Changes were similar for different genders and socioeconomic groups, but differed by ethnicity: the most pronounced increase was among White CYP (relative ratio 1.88, 95% CI 1.59, 2.24), compared with no clear change for Black and minority ethnic CYP (relative ratio 0.85, 95% CI 0.52, 1.39). Comorbid psychiatric conditions were present in over a third of CYP with emotional disorders, with the most common being conduct disorder.
Conclusions
Between 2004 and 2017, the increase in emotional disorders among CYP in England was largely driven by anxiety disorders. Socioeconomic inequalities did not narrow. Disaggregating by ethnicity, change was evident only in White CYP, suggesting differential trends in either risk exposure, resilience or reporting by ethnicity.
Many marine invertebrates are intermediate hosts to parasites. As some of these parasites may influence host behaviour and act as cryptic agents involved in mass mortality, knowledge of their presence, dynamics, and life cycles is important. Our aim with the present study is to provide a survey of parasites in subtidal cockles in the Limfjorden (Denmark), to examine their influence on cockles, and to assess their possible role in the surfacing of cockles, as this phenomenon is considered a prelude to mortality. The trematode fauna of the studied subtidal population was poor in species, but about 19% of the examined cockles in late summer and autumn were infected by Monorchis parvus – a species not previously reported from cockles in Danish waters. Heavily infected cockles were filled with small, undulating, worm-like sporocysts, each filled with metacercariae. From August to November, the number of metacercariae in sporocysts increased, and at a certain point, the growing stock of sporocysts is supposed to reach a level where the cockle is unable to perform vital life functions. Our data show that infected individuals exhibit less annual shell growth than uninfected ones. There was no significant difference in the prevalence of M. parvus between unburied and buried cockles. Cockle-eating fish from the family Sparidae are known as final hosts to M. parvus, but these fish do not occur in Danish waters. Therefore, the record-high presence of M. parvus in cockles from the Limfjorden is surprising, and we consider alternative life cycle options for this trematode.
Opioid use disorder (OUD) is a medical condition associated with problematic opioid use, leading to addiction and severe life impairments. This research delivers an in-depth evaluation of OUD burden and trends at global, regional and national levels.
Methods
This study analysed the global burden of OUD from 1990 to 2021 using data from the 2021 Global Burden of Diseases, Injuries, and Risk Factors Study. Key metrics included age-standardized prevalence, incidence, mortality and disability-adjusted life years (DALYs), disaggregated by gender, age, region, country and socio-demographic index (SDI) quintiles. The average annual percentage change described trends, while the age-period-cohort model evaluated age, period and cohort effects. A Bayesian Age-period-cohort model predicted future OUD trends from 2022 to 2040.
Results
In 2021, the global burden of OUD remained substantial, with a total of 16,164,876 cases and a prevalence of 154.59 cases per 100,000 population (95% uncertainty interval [UI]: 131.06–181.26). In 2021, the global incidence of OUD reached 1,942,525 cases (95% UI: 1,643,342–2,328,363), and its global mortality reached 99,555 deaths (95% UI: 92,948–108,050), with DALYs amounting to 11,218,519 (95% UI: 9,188,658–13,159,551). Regionally, high SDI regions, particularly in the High-income North America, exhibited the greatest burden. Among countries, the United States faced the most severe burden and increase, with the highest prevalence (2014.62 per 100,000), incidence (151.84 per 100,000), mortality (15.37 per 100,000) and DALYs (1594.63 per 100,000), and all APPC values exceeding 5%. Males aged 20–39 years were the most affected demographic. However, forecasts indicate that the OUD burden among females will significantly increase over the next 20 years, with the prevalence and incidence expected to rise by 39% and 49%, respectively.
Conclusions
The global burden of OUD has statistically significantly increased from 1990 to 2021. There are marked disparities across regions, countries and SDI levels. High-SDI regions, particularly High-income North America, bear the heaviest burden, with young males (aged 20–39 years) being the most affected groups. However, caution should be exercised regarding the female population, as the number of affected individuals is rapidly increasing.