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Prevalence and risk factors of nutritional anaemia among adolescents in India: a systematic review with meta-analysis of prevalence.

BACKGROUND: Nutritional anaemia is a major public health concern among adolescents in India, threatening physical growth, cognitive development, and future maternal health. This systematic review with meta-analysis of prevalence aimed to estimate the pooled prevalence of nutritional anaemia among Indian adolescents aged 10-19 years and identify key associated risk factors. METHODS: A systematic search was conducted across PubMed, Embase, Web of Science, and Scopus up to February 2025. Data were extracted on study design, setting, diagnostic methods, prevalence, and risk factors. Quality was assessed with a modified Newcastle-Ottawa Scale. A random-effects meta-analysis estimated pooled prevalence, with subgroup analyses by state and gender, and pooled odds ratios for risk factors. RESULTS: Forty-five studies encompassing diverse Indian regions and 159,979 adolescents were included. The pooled prevalence of nutritional anaemia was 56% (95% CI: 49%-63%), with higher rates among girls (62%) than boys (39%). Iron deficiency (OR 2.38-4.68), other micronutrient deficiencies, low socioeconomic status, poor dietary diversity, female gender, and inadequate supplementation were consistently associated with higher anaemia risk. CONCLUSION: Nutritional anaemia impacts more than half of Indian adolescents, with notable regional and gender differences. Its complex nutritional, socioeconomic, and behavioural causes demand targeted, context-specific interventions to enhance adolescent health nationwide.

Humans

The prevalence of middle ear disease among learning impaired children. Does a higher prevalence indicate an association?

The prevalence of middle ear disease among children who are educationally classified as learning disabled as compared to that found in normal children is discussed. A higher incidence of middle ear pathology was found among the learning impaired children. The potentially hazardous effects that middle ear disease can have upon academic and linguistic development are emphasized.

Adolescent

Psychiatric status and the disorders of thyroid function. I. Prevalence of goitre in a group of psychiatric patients. I. The prevalence of goitre in a group of psychiatric patients.

All (478) indigenous Zambian patients who were in hospital on a particular day in January 1976 were examined by the authors for goitre. 34.4 per cent of all adult female patients and 23.2 per cent of all adult male patients had goitre. However, 57.6 per cent of all female patients with effective illness and 77.0 per cent of all male patients with paranoid psychosis were found to have goitre. The association between affective illness and paranoid psychosis on the one hand and goitre on the other was found to be statistically significnat at the 0.1 per cent level. It is suggested that further work should be done to find out what proportion of patients with depression or pananoia have sub-clinical or borderline hypothyroidism.

Affective Symptoms

Prevalence of unruptured intracranial aneurysms according to comorbidities, risk factors, country, and time period: a systematic review and meta-analysis.

BACKGROUND: The incidence of aneurysmal subarachnoid haemorrhage declined between 1980 and 2010, which coincided with a decline in smoking and prevalence of hypertension. We aimed to investigate whether the decrease in subarachnoid haemorrhage incidence is paralleled by declines in unruptured intracranial aneurysm (UIA) prevalence. METHODS: For this systematic review and meta-analysis, we searched Embase, PubMed, and Web of Science for articles published in any language from Jan 1, 2011 to Dec 31, 2025, and reassessed 68 articles published before March 1, 2011 from a 2011 systematic review and meta-analysis. Articles were eligible for inclusion if they used a cross-sectional or case-control design and provided the crude number of participants and those with UIA. We only included studies reporting numbers of UIA separately from ruptured aneurysms and with ten or more patients. Summary data were independently extracted by JD with AZ or CB and conflicts were resolved by GJER. The primary outcome was proportion of participants with UIA. Relative to a hypothetical reference population (mean age 50 years, 50% women, and no comorbidities), age and/or sex-adjusted prevalence ratios (PRs) for regions, comorbidities, and risk ratios (RRs) for female sex, smoking, and hypertension were estimated using generalised linear mixed models. A time trend analysis was done by binomial meta regression using the mid-year of data acquisition. We assessed the certainty of evidence using GRADE. The study was registered with PROSPERO, number CRD420261296728. FINDINGS: Our search screened 4708 studies. 67 reassessed and 95 newly identified articles, reporting on 316 131 participants and 11 822 people with UIAs, were included in our meta-analysis. In the reference population, the estimated prevalence of UIAs was 3·9% (95% CI 3·0-5·1). The prevalence of UIAs in individuals with atherosclerosis was 5·5% (4·7-6·4; 2229 of 40970 participants) and the adjusted PR was 1·3 (95% CI 0·8-2·0) compared with the reference population. For positive family history of aneurysmal subarachnoid haemorrhage (aSAH) or UIA, the UIA prevalence was 7·9% (5·6-11·1; 412 of 4252 participants) and the adjusted PR was 2·4 (0·5-11·2). For connective-tissue disorder, the UIA prevalence was 10·3% (6·5-16·0; 94 of 879 participants) and the adjusted PR was 3·9 (2·0-7·6). For autosomal dominant polycystic kidney disease (ADPKD), the UIA prevalence was 12·8% (9·2-17·6; 293 of 1990 participants) and the adjusted PR was 4·4 (1·5-12·6). RRs were for current smoking 1·4 (1·2-1·6; 798 of 27911 participants), for having hypertension 1·6 (1·5-1·7, 4043 of 83053 participants), and for female sex 1·9 (1·8-2·0; 3415 of 65020 women and 2122 of 76130 men). In studies on healthy individuals with MR angiography or CT angiography as imaging modality, the prevalence in 2016-2022 was 6·6% (6·3-6·8; 2904 of 41191 participants). The adjusted PR was 1·8 (1·1-2·8) for 2016-2022 versus 2002-2015. Prevalence of UIAs of 5 mm or larger was 0·7% (0·6-0·8) in 2002-2015 and 1·4% (1·0-1·9) in 2016-2022. The UIA prevalence did not differ between countries. τ2 showed significant heterogeneity between studies. The certainty of the evidence ranged from very low to moderate. INTERPRETATION: Prevalence of UIA is increasing, particularly over the past two decades. This increase is only in part explained by improved detection of small UIAs and an ageing population, and other factors-such as environmental-are likely involved. Alongside patients with ADPKD and a positive family history of aSAH, patients with connective-tissue disorders had a higher prevalence of UIA than the reference population. Our findings warrant further investigation into the potential benefit of personalised screening and management strategies in groups at high risk for having UIAs. FUNDING: None.

Humans

Worldwide prevalence of haemorrhoids: a systematic review and meta-analysis.

BACKGROUND: Haemorrhoidal disease (HD) is one of the most common anorectal disorders globally, significantly impacting individuals' quality of life and productivity. Despite its importance, global prevalence remains unclear due to limited population-specific studies. This study aimed to systematically assess the global prevalence of HD through a systematic review and meta-analysis. METHODS: We conducted a systematic review and meta-analysis by searching PubMed, Scopus, Embase, Web of Science, and Google Scholar up to March 31, 2025, without language restrictions. Studies reporting prevalence of haemorrhoids in general, clinical, or high-risk populations were included. Exclusion criteria comprised studies lacking total sample size, focusing on other anorectal conditions, or using duplicate or insufficient data. Four independent reviewers extracted and appraised study quality using the Joanna Briggs Institute tool. The primary outcome was pooled point prevalence of HD, analyzed using a random-effects model with 95% confidence intervals (CIs). The study was registered in PROSPERO (CRD420251045600). RESULTS: From 6,312 records, 150 studies (210 datasets) comprising 8,960,338 individuals were included. The global pooled point prevalence was 25.92% (95% CI: 22.62-29.22). Lifetime prevalence was 27.19% (95% CI: 14.77-39.60), and one-year prevalence was 21.65% (95% CI: 14.33-28.97). Prevalence was higher in women (27.33%, 95% CI: 21.84-32.82) than in men, and highest in the African region 28.07% (95% CI: 15.34-40.79). Invasive diagnostic methods (28.05%, 95% CI: 23.86-32.26) yielded higher prevalence estimates than non-invasive methods. Also, factors showing associations with HD in unadjusted analyses include older age, obesity, pregnancy, diabetes, family history, constipation, and hypertension. CONCLUSION: HD remains a prevalent condition globally, with minor variation across regions. The burden is consistent regardless of socioeconomic context. Diagnostic method and population characteristics influence prevalence estimates. These findings underscore the importance of targeted prevention and early intervention strategies, especially for at-risk groups.

Humans

Estimated prevalence and distribution of causes of immune-mediated hypertrophic pachymeningitis in São Paulo, Brazil.

BACKGROUND: The prevalence of hypertrophic pachymeningitis (HP) remains poorly defined worldwide. In Japan, the estimated prevalence is 0.949 cases per 100,000 inhabitants, with most cases related to ANCA-associated vasculitis or IgG4-related disease. In contrast, epidemiological data from other regions, including Latin America, are scarce. METHODS: This study was conducted at a tertiary referral center in the city of São Paulo, Brazil. The prevalence of HP was estimated by comparison with the known prevalence of multiple sclerosis (MS), based on the number of patients with each condition followed at our institution. The etiological distribution of HP was also analyzed. In addition, HP prevalence was compared with that of tuberculous meningoencephalitis, a compulsory notifiable disease and a well-established cause of chronic meningitis in Brazil, using data from the national surveillance system (SINAN). RESULTS: We identified 55 patients with HP: 36 (65%) idiopathic, 10 (18%) IgG4-related disease, 4 (7%) ANCA-associated pachymeningitis, 4 (7%) probable or definite neurosarcoidosis, and 1 (2%) secondary to rheumatoid arthritis. Among 968 registered MS patients and assuming an MS prevalence of 15 per 100,000 inhabitants in São Paulo, the estimated HP prevalence was 0.85 per 100,000 inhabitants. This estimate was comparable to the prevalence of tuberculous meningoencephalitis in the same region. CONCLUSION: The estimated prevalence of HP in São Paulo (0.85 per 100,000) is consistent with reports from other regions and is comparable to that of tuberculous meningeal disease, although with a distinct etiological profile. IgG4-related disease was the most frequent systemic association, differing from previous reports. ANCA-associated HP appears to be less frequent than in other geographic regions, possibly reflecting differences in disease phenotype. Key Points • The estimated prevalence of HP in São Paulo was 0.85 per 100,000 inhabitants. • IgG4-related disease was the most common systemic disease identified among patients with HP. • ANCA-associated HP was less common than reported in Asian and European cohorts. • The prevalence of HP was comparable to that of tuberculous meningoencephalitis in São Paulo.

Humans

The global prevalence of horizontal strabismus: A systematic review and meta-analysis with a focus on ethnic variation.

The prevalence of the 2 types of horizontal strabismus, esotropia and exotropia, varies considerably between studies. This variability has been attributed to factors such as geography/environment, research methodology, age of study subjects, and/or ethnicity. Comprehensive estimates of regional and global prevalences of esotropia and exotropia are lacking, making it difficult to recognize true patterns, trends, and etiologies. We compile prevalences and ratios of esotropia to exotropia from 315 population-based studies and 374 clinic-based studies. We analyze data to assess effects of ethnicity, geography, age, and we identify generational changes of horizontal strabismus. Major ethnicities differ in patterns and ratios of esotropia and exotropia prevalence, not only in Caucasians and East Asians, but also Latinos/Hispanics, South Asians, Africans, and Native Americans. Compared to population-based studies, clinic-based studies underestimate exotropia frequency. By weighing prevalences according to the population size of ethnicities, we estimate the worldwide prevalence of horizontal strabismus in the current generation at 1.81% (138.5 million people), comprising 60.0 million people with esotropia (0.67%) and 87.5 million with exotropia (1.14%). In the previous generation, the worldwide prevalence of horizontal strabismus was 1.64% (86.5 million people), comprising 50.5 million with esotropia (0.96%) and 36.0 million with exotropia (0.68%). Esotropia and exotropia prevalences differ between generations within the same ethnicity, indicating that extrinsic factors can modify the underlying intrinsic (genetic) disposition.

Humans

Global prevalence of metabolic syndrome in adults with obstructive sleep apnea: a systematic review and meta-analysis.

STUDY OBJECTIVES: Metabolic syndrome (MetS) is considered to exhibit increased prevalence among adults with obstructive sleep apnea (OSA), but the reported prevalence estimates among such patients vary. Thus, this systematic review and meta-analysis aimed to investigate the global prevalence of MetS in adults with confirmed OSA. MATERIALS AND METHODS: Ovid Medline, Embase, CINAHL, and the Cochrane Library databases were searched for all primary studies published in English that used standard polysomnography for OSA diagnosis and reported MetS estimates. At least two reviewers independently screened for eligible studies, extracted data, and graded the risk of bias using the Risk of Bias Assessment Tool for Non-randomised Studies. Three-level random-effects model was applied for the meta-analysis, reporting pooled prevalence estimate with 95% confidence intervals (CIs). Pre-specified subgroup analyses and meta-regression were also performed. Heterogeneity was quantified using I2 and chi-square statistics. RESULTS: A total of 102 studies were eligible for inclusion (34&#x2009;013 adults with OSA from 28 countries). The combined MetS prevalence was 55.4% (95% CI: 51.0%, 59.8%). Considerable heterogeneity was noted among the included studies (I2&#x2009;=&#x2009;97.8%), whilst the risk of bias ranged from low to high. Subgroup analysis examining the effects of geographic region, study design, MetS definition, and apnea-hypopnea index threshold showed a significant variation in prevalence estimates across most subgroups (p&#x2009;<&#x2009;0.0001). Meta-regression analysis indicated a positive association between mean body mass index (&#x3b2;&#x2009;=&#x2009;0.0772, t&#x2009;=&#x2009;4.56, p&#x2009;<&#x2009;0.0001) and MetS prevalence. CONCLUSIONS: MetS has a high prevalence among adults with polysomnography-confirmed OSA, underscoring the need for prompt MetS screening in these patients. Future longitudinal and genetic/mechanistic studies should investigate the factors accounting for this association. PROSPERO REGISTRATION NUMBER: CRD420251073055.

Humans

Prevalence and causes of anemia among older adults in India: findings from wave 2 of the Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD).

Anemia among older adults aged&#x2009;&#x2265;&#x2009;60 years is a well-described risk factor that increases the risk of falls, cardiovascular diseases, and mortality. In India, objectively measured national estimates of anemia prevalence and the causes of anemia among older adults are lacking. The Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) collected venous blood samples from a nationally representative sample of 3,252 individuals in wave 2 of the study. Out of these, 3,009 samples were used to estimate national prevalence and regional differences in anemia prevalence and its underlying causes. Anemia was defined as hemoglobin&#x2009;<&#x2009;13&#xa0;mg/dl in males and <&#x2009;12&#xa0;mg/dl in females and further categorized into nutritional and non-nutritional anemia based on several nutritional (ferritin, Vitamin B12, and folate), inflammatory (ferritin, C-reactive protein), and renal (serum creatinine) biomarkers. The overall national anemia prevalence was 49.92%. Anemia prevalence was significantly higher among women (53.9%) than men (45.8%). Among those with anemia, nutritional anemia was found in 63.5% of the respondents, with isolated iron deficiency anemia being the most common cause (51.8%). Among the non-nutritional category, anemia of chronic disease was the most common type (31.4%). About 10% of all anemia cases could not be classified into either category using the available data. Regional differences were seen with the highest prevalence of anemia in Assam, West Bengal, Jharkhand, and Odisha, and the lowest prevalence (<&#x2009;30%) in Jammu & Kashmir and Haryana. Multivariate adjustment showed that age, sex, and region of residence are independently associated with anemia status. The study provides valuable insights into the overall anemia prevalence among older adults in India, its underlying causes, and regional differences to lay a strong foundation for making informed decisions toward anemia control in India.

Humans

Prevalence of Claudin 18.2 Expression in Gastric and Gastroesophageal Junction Adenocarcinoma: A Systematic Review and Meta-Analysis.

BACKGROUND: Claudin 18 isoform 2 (CLDN18.2) has emerged as a clinically validated therapeutic target in gastric and gastroesophageal junction (GEJ) adenocarcinoma following the regulatory approval of zolbetuximab in combination with first-line chemotherapy. Accurate prevalence data at the clinically validated immunohistochemical threshold are essential for patient selection, healthcare resource planning, and treatment strategy. Reported prevalence estimates vary widely across studies due to differences in populations, methodologies, and immunohistochemical protocols. This systematic review and meta-analysis aimed to generate a robust pooled prevalence estimate of CLDN18.2 expression at the threshold used in pivotal phase III trials. METHODS: PubMed, Embase, and the Cochrane Library were searched from database inception through March 12th, 2026. Studies reporting CLDN18.2 expression in gastric or gastroesophageal junction adenocarcinoma using the &#x2265;&#x2009;75% moderate-to-strong membranous staining threshold were included. Prevalence proportions were pooled using a random-effects model with logit transformation and restricted maximum-likelihood estimation of between-study variance. Heterogeneity was assessed using the I&#xb2; statistic and Cochran's Q test, and a 95% prediction interval was calculated. Pre-specified subgroup analyses assessed antibody clone and geographic region, with additional exploratory analyses according to disease setting and specimen type. Sensitivity analyses were performed to assess the robustness of the pooled estimate. RESULTS: Twenty-two predominantly retrospective cohort studies comprising 12,173 patients were included. The pooled prevalence of CLDN18.2 positivity using a random-effects model was 33.99% (95% CI: 30.13%-38.07%; 95% prediction interval: approximately 18%-55%), with high between-study heterogeneity (I&#xb2; = 92.4%). Subgroup analysis by antibody clone showed no statistically significant difference between studies using the 43-14&#xa0;A clone (32.79%, 95% CI: 28.86%-36.97%) and those using other reported antibody clones (41.74%, 95% CI: 26.76%-58.42%; p&#x2009;=&#x2009;0.281). One study with an unreported antibody clone was excluded from this subgroup analysis. Geographic subgroup analysis excluding the multinational Shitara et al. cohort demonstrated a non-significant trend toward higher prevalence in non-Asian populations (37.85%, 95% CI: 31.59%-44.54%) compared with Asian populations (32.10%, 95% CI: 27.28%-37.34%; p&#x2009;=&#x2009;0.169). All three sensitivity analyses confirmed robustness of the pooled estimate. No significant evidence of publication bias was detected (Egger's test p&#x2009;=&#x2009;0.56). CONCLUSIONS: Approximately one-third of patients with gastric and GEJ adenocarcinoma express CLDN18.2 at the clinically validated&#x2009;&#x2265;&#x2009;75% threshold. However, because the included studies encompassed heterogeneous disease settings and were predominantly HER2-unselected, the pooled estimate should not be interpreted directly as the proportion of patients eligible for zolbetuximab. The estimate was robust across sensitivity analyses and provides an evidence base for understanding CLDN18.2 prevalence and biomarker-testing requirements. Standardisation of immunohistochemical assessment methods is warranted to reduce between-study heterogeneity in future research.

Humans

A systematic review and meta-analysis to estimate the global prevalence of leptospirosis in sheep.

Leptospirosis in sheep is a zoonotic concern considering sheep may act as potential reservoirs for Leptospira spp. infection to humans. This study aimed to estimate the pooled prevalence of leptospirosis in sheep worldwide. A comprehensive literature search was conducted across databases following PRISMA guidelines. Meta-analyses were performed using a random effect model in R software (version 4.3.1) to calculate pooled prevalence with 95% confidence intervals (CI). Subgroup analyses were performed based on prevalence types, diagnostic methods and continental regions to explore sources of heterogeneity. A total of 138 studies comprising 54,174 samples and 10,299 positive detections were included in this study. The global pooled prevalence of leptospirosis in sheep was 15.69% (95% CI: 12.69-19.25) with overall heterogeneity (I2) 98%. The prediction interval ranged from 1.09% to 75.91%, indicating wide inter-study variability. The seroprevalence was 16.16% (95% CI: 12.91-20.04) and infection prevalence was 12.98% (95% CI: 8.07-20.22), showing no significant difference (P&#xa0;=&#xa0;0.40). In addition, the prevalence of leptospirosis in sheep differed significantly across diagnostic methods and continents (P&#xa0;<&#xa0;0.01), indicating substantial variation influenced by both methodological and geographical factors. The funnel plot revealed marked asymmetry, suggesting potential publication bias which was confirmed by Egger's regression test (P&#xa0;<&#xa0;0.01). In conclusion, leptospirosis is widely prevalent in sheep globally, with marked geographical and methodological heterogeneity. These findings highlight the epidemiological importance of sheep in leptospirosis transmission and underscore the need for improved surveillance, standardized diagnostic approaches, and targeted control strategies within a One Health framework.

Animals

Prevalence of psychosis in South Asia: A systematic review and meta-analysis.

BACKGROUND: Psychotic disorders are a major contributor to global disability, yet prevalence data from South Asia which inhabits a quarter of the world's population, remain limited. Reliable estimates are essential for health service planning, policy, and closing the substantial treatment gap. This review provides the first comprehensive synthesis of psychosis prevalence across South Asia. METHODS: We searched PubMed, Embase, Web of Science, Global Health, and Medline to 18 December 2024 for DSM- or ICD-based prevalence studies in Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. Cross-sectional and longitudinal studies in community or clinical populations were included. Study quality was assessed using the Joanna Briggs Institute checklist. Random-effects meta-analyses estimated pooled prevalence using the logit transformation. Heterogeneity was explored with meta-regression of key methodological variables (publication year, diagnostic system, residential setting). FINDINGS: Thirty-one studies from five countries were included. Among community-dwelling adults, pooled point prevalence was 0.85% and lifetime prevalence was 1.40%, with inter-country differences (India 1.18%, Pakistan 2.13%, Nepal 2.90%). Clinical samples showed substantially higher proportions of individuals with psychosis in service settings (11.44%), reflecting concentration of cases in treatment-seeking samples. Data for children and adolescents were limited and summarised narratively. Heterogeneity was high across meta-analyses, and exploratory meta-regression did not identify any significant moderators. INTERPRETATION: Psychosis prevalence estimates in South Asia appear higher than global averages but should be interpreted cautiously due to substantial heterogeneity and methodological variation; nevertheless, they highlight the need for culturally sensitive screening, improved detection, and strengthened mental health services.

Humans