Background and Objectives: Despite frequent references to the high prevalence of vitamin D deficiency in Kazakhstan, a comprehensive synthesis of existing research on this issue among adults is lacking. This systematic review and meta-analysis aim to address this gap by determining the mean prevalence of vitamin D deficiency among adults in Kazakhstan. A secondary objective is to evaluate whether the prevalence differs between healthy adults and those with chronic conditions. Materials and Methods: A systematic search was conducted in PubMed, Scopus, ScienceDirect, Web of Science, and Google Scholar by two independent researchers using the keywords: “vitamin D” AND “Kazakhstan”, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were included if they reported the prevalence of vitamin D in adults in Kazakhstan, defined as a blood level of 25-hydroxyvitamin D 25(OH)D below 20 ng/mL. Results: Seven studies were included in this review, encompassing 3616 individuals, of whom 2239 had vitamin D deficiency. Using a random-effects model, the pooled mean prevalence of vitamin D deficiency among adults with chronic conditions was 60% (95% CI, 38–79%), with high heterogeneity. Similarly, the analysis of five studies involving healthy adults revealed a pooled mean prevalence of 55% (95% CI, 38–70%), also with high heterogeneity. Overall, the pooled mean prevalence of vitamin D deficiency in the adult population was 57% (95% CI, 45–69%). Conclusions: This analysis indicates a high prevalence of vitamin D deficiency among adults in Kazakhstan, with 57% of the population affected. Addressing this issue requires a multifaceted approach, including policy reforms that consider the impact of time zone changes on sunlight exposure and the active involvement of nurse practitioners in preventive strategies.

Background and Objectives: Kazakhstan’s unique geographic, dietary, and cultural factors contribute to the widespread occurrence of vitamin D deficiency across the entire country population, particularly among children. This study aims to assess the mean prevalence of vitamin D deficiency in children in Kazakhstan and determine whether it differs between healthy and non-healthy children, as well as between infants and older age groups. Materials and Methods: A comprehensive literature search was performed across five databases by two researchers. Studies were eligible if they were observational and provided the number of children with serum 25-hydroxyvitamin D levels below 20 ng/mL out of the total number of children assessed in Kazakhstan. Results: Eleven studies were included in the analysis, assessing 1396 children, of whom 714 had the outcome of interest. The pooled mean estimate of vitamin D deficiency among children was 56% (95% CI, 46–65%), with particularly concerning rates among infants at 65% (95% CI, 44–82%). No substantial differences were observed between healthy and non-healthy children. Conclusions: The prevalence of vitamin D deficiency among children is alarmingly high. These results highlight the urgent necessity of tackling vitamin D deficiency as a public health priority. Incorporating vitamin D deficiency prevention into Kazakhstan’s national healthcare program is vital for improving child health outcomes and reducing the long-term burden of associated complications.

Background/Objectives: Nurses and nursing students are central to HIV prevention and care, but studies of their general HIV-related knowledge, attitudes, and practices use heterogeneous populations, instruments, scoring systems, and thresholds. This review had three objectives: (1) to meta-analyze, separately, the prevalence of study-defined high/good general HIV knowledge, mean general knowledge scores, prevalence of study-defined positive/favorable general attitudes, and mean favorable-attitude scores; (2) to synthesize HIV-related clinical-practice findings narratively when measures were not comparable; and (3) to explore whether pooled knowledge and attitude estimates differed between practicing nurses and nursing students. General outcomes excluded narrowly focused PrEP-, PEP-, stigma-only, and item-level constructs. Methods: PubMed/MEDLINE, Scopus, PsycINFO, and CINAHL Complete were searched for eligible quantitative studies. Four knowledge and attitude outcomes were meta-analyzed in separate random-effects models; practice outcomes were not pooled. Heterogeneity, 95% prediction intervals, leave-one-out influence, possible small-study effects, subgroup differences, and certainty of evidence were assessed. Results: Thirty-four studies were included. The pooled prevalence of high/good HIV-related knowledge was 52.4% (95% CI 30.4–73.5%; I² = 97.5%; 95% prediction interval 3.6–97.0%), and the pooled mean knowledge score was 66.3% of the possible score (95% CI 60.8–71.8%; I² = 99.8%; prediction interval 40.0–92.5%). Positive/favorable attitudes had a pooled prevalence of 41.6% (95% CI 7.3–86.5%; I² = 99.1%; prediction interval 0.0–99.9%), and the pooled mean favorable-attitude score was 48.1% of the possible range (95% CI 41.9–54.2%; I² = 99.7%; prediction interval 21.3–74.8%). Thus, all four meta-analyses showed extreme heterogeneity and wide prediction intervals. Prespecified subgroup tests did not detect nurse-versus-student differences for either knowledge outcome or favorable-attitude prevalence; a higher pooled mean favorable-attitude score among students was observed in one exploratory comparison. Four studies reported non-equivalent practice indicators (16.0–85.3%), which were not pooled. Certainty was very low for all meta-analyzed outcomes. Conclusions: The pooled estimates should be interpreted as descriptive summaries across heterogeneous operationalizations rather than as precise global nursing-workforce benchmarks or common competency thresholds. More standardized measurement, objective assessment of clinical practice, and longitudinal and interventional research are needed.

Background/Objectives: The aim of this study was to systematically synthesize and quantitatively estimate the mean serum 25-hydroxyvitamin D concentrations across populations in Kazakhstan and to examine variations according to age group, health status, and geographic region. In addition, we specifically evaluated healthy subgroups to establish reference estimates that may be useful for future epidemiological surveillance and public health planning. Methods: A systematic review and meta-analysis was conducted in accordance with the PRISMA 2020 guidelines. PubMed, Scopus, ScienceDirect, and Google Scholar were searched through March 2026 without date restrictions. Studies reporting the mean serum vitamin D concentrations among Kazakhstani populations were included. Random-effects meta-analysis was performed in R. Subgroup analyses were conducted by age group, health status, and geographic region. Meta-regression, influence diagnostics, publication bias assessment, JBI risk-of-bias evaluation, and GRADE certainty-of-evidence assessment were performed. Results: Sixteen studies comprising 28 groups and 5771 participants were included. The pooled mean serum 25(OH)D concentration in the overall cohort was 22.3 ng/mL (95% CI: 19.3–25.3), while the healthy cohort demonstrated a slightly higher pooled mean of 24.4 ng/mL (95% CI: 20.3–28.4). Adolescents had the lowest vitamin D levels among all age groups. Significant regional variability was observed, and meta-regression identified male participant proportion as a significant moderator (p = 0.03). Heterogeneity was extremely high across analyses (I² ≈ 99.9%). Conclusions: Mean serum 25(OH)D concentrations were generally within the insufficient range across the included study groups in Kazakhstan, including healthy subgroups. However, because the certainty of evidence was very low and between-study heterogeneity was extreme, the findings should be interpreted cautiously. These results support the need for standardized national surveillance and locally evaluated public health policy considerations, including targeted supplementation for high-risk groups, screening strategies where clinically indicated, and assessment of food fortification options.