Tag: statistics

PLoS Negl Trop Dis. 2022 Jun 9;16(6):e0010456. doi: 10.1371/journal.pntd.0010456. Online ahead of print.

ABSTRACT

BACKGROUND: Estimating community level scabies prevalence is crucial for targeting interventions to areas of greatest need. The World Health Organisation recommends sampling at the unit of households or schools, but there is presently no standardised approach to scabies prevalence assessment. Consequently, a wide range of sampling sizes and methods have been used. As both prevalence and drivers of transmission vary across populations, there is a need to understand how sampling strategies for estimating scabies prevalence interact with local epidemiology to affect the accuracy of prevalence estimates.

METHODS: We used a simulation-based approach to compare the efficacy of different scabies sampling strategies. First, we generated synthetic populations broadly representative of remote Australian Indigenous communities and assigned a scabies status to individuals to achieve a specified prevalence using different assumptions about scabies epidemiology. Second, we calculated an observed prevalence for different sampling methods and sizes.

RESULTS: The distribution of prevalence in subpopulation groups can vary substantially when the underlying scabies assignment method changes. Across all of the scabies assignment methods combined, the simple random sampling method produces the narrowest 95% confidence interval for all sample sizes. The household sampling method introduces higher variance compared to simple random sampling when the assignment of scabies includes a household-specific component. The school sampling method overestimates community prevalence when the assignment of scabies includes an age-specific component.

DISCUSSION: Our results indicate that there are interactions between transmission assumptions and surveillance strategies, emphasizing the need for understanding scabies transmission dynamics. We suggest using the simple random sampling method for estimating scabies prevalence. Our approach can be adapted to various populations and diseases.

PMID:35679325 | DOI:10.1371/journal.pntd.0010456

PLoS One. 2022 Jun 9;17(6):e0265341. doi: 10.1371/journal.pone.0265341. eCollection 2022.

ABSTRACT

The fast development of technologies in today’s world is accompanied by the mushrooming of digital platforms constituting the core of the ecosystem of sharing economy. This multifaceted phenomenon and its ever-increasing presence have become a subject of public interest and debate, as well as encouraging research and scientific discourse. The article presents the results of the first study of Poles’ participation in sharing economy derived from a questionnaire survey of a representative sample (n = 1000). The purpose of the study was to characterise Poles participating in the digital economy and to determine how they differ in the use of sharing platforms depending on their age group and generation. The analysis has shown that the rates of Poles participating in the digital economy are the smaller, the older the age group, and that a rising number of the users of digital economy solutions translates into greater acceptance of sharing platforms. Among the oldest Poles, 70% do not participate in the digital economy and as much as 80% in the sharing economy. The numbers sharply contrast with generations Z and Y that participate in the sharing economy almost without exception. The most popular of sharing services turned out to be accommodation reservation indicated by every third respondent.

PMID:35679317 | DOI:10.1371/journal.pone.0265341

PLoS One. 2022 Jun 9;17(6):e0269805. doi: 10.1371/journal.pone.0269805. eCollection 2022.

ABSTRACT

Carotid atherosclerotic plaque rupture and its sequelae are among the leading causes of acute ischemic stroke. The risk of rupture and subsequent thrombosis is, among others, determined by vulnerable plaque characteristics and linked to activation of the immune system, in which neutrophil extracellular traps (NETs) potentially play a role. The aim of this study was to investigate how plaque vulnerability is associated with NETs levels. We included 182 patients from the Plaque At RISK (PARISK) study in whom carotid imaging was performed to measure plaque ulceration, fibrous cap integrity, intraplaque hemorrhage, lipid-rich necrotic core, calcifications and plaque volume. Principal component analysis generated a ‘vulnerability index’ comprising all plaque characteristics. Levels of the NETs marker myeloperoxidase-DNA complex were measured in patient plasma. The association between the vulnerability index and low or high NETs levels (dependent variable) was assessed by logistic regression. No significant association between the vulnerability index and NETs levels was detected in the total population (odds ratio 1.28, 95% confidence interval 0.90-1.83, p = 0.18). However, in the subgroup of patients naive to statins or antithrombotic medication prior to the index event, this association was statistically significant (odds ratio 2.08, 95% confidence interval 1.04-4.17, p = 0.04). Further analyses revealed that this positive association was mainly driven by intraplaque hemorrhage, lipid-rich necrotic core and ulceration. In conclusion, plaque vulnerability is positively associated with plasma levels of NETs, but only in patients naive to statins or antithrombotic medication prior to the index event.

PMID:35679310 | DOI:10.1371/journal.pone.0269805

PLoS One. 2022 Jun 9;17(6):e0269601. doi: 10.1371/journal.pone.0269601. eCollection 2022.

ABSTRACT

INTRODUCTION: The quality of tuberculosis laboratory services in health facilities is a mandatory component of detecting active pulmonary TB cases and treatment follow-up. However, ensuring the quality of laboratory test results is a concern. This study aimed to assess the quality assurance practices in the tuberculosis diagnostic health facilities of Ethiopia.

MATERIALS AND METHODS: A cross-sectional study was conducted from October 2018 to March 2019 at nine governmental TB-culture laboratories and 34 randomly selected GeneXpert® MTB/RIF (Xpert® MTB/RIF) testing health facilities in Ethiopia. Participating health facilities were interviewed and laboratory documents and records present since 2017 were observed. Prior to the data collection, training was given to the data collectors. Descriptive statistics were used to produce results and were presented with tables and graphs.

RESULTS: From a total of 34 Xpert® MTB/RIF testing laboratories, 50% run Internal Quality Control (IQC) for Acid-Fast Bacillus (AFB) Microscopy and 67.6% had lot-to-lot verification of staining reagents. For the Xpert® MTB/RIF assay, a lot-to-lot verification of cartridge and method validation was performed only in 8.8%and 20.6% of Xpert® MTB/RIF testing laboratories respectively. All TB-culture laboratories included in the study ran negative control (start and end IQC) during TB-culture sample processing and performed lot-to-lot verification for Mycobacteria Growth Indicator Tube (MGIT) in 88.9% of TB-culture laboratories. External Quality Assessment (EQA) Proficiency Testing (PT) for AFB microscopy is practiced in 79.4% Xpert® MTB/RIF testing laboratories and 100.0% for the Xpert® MTB/RIF assay. TB-Culture PT participation practice among TB-culture laboratories was 88.9%. A major challenge for health facilities during PT participation was the AFB PT-sample transportation delay (40.7%) and the Xpert® MTB/RIF assay EQA-PT feedback missing (38.2%).

CONCLUSION: This assessment reveals that IQC for AFB microscopy, lot-to-lot verification, method validation, and equipment calibration were not well-practiced. The majority of TB diagnostic health facility laboratories had EQA-PT participation practice, but a significant gap in PT-sample transportation and missing feedback was identified.

PMID:35679308 | DOI:10.1371/journal.pone.0269601

PLoS One. 2022 Jun 9;17(6):e0269263. doi: 10.1371/journal.pone.0269263. eCollection 2022.

ABSTRACT

The study was undertaken in Gedeo zone with the aim to identify traditional sheep breeding practices. Three potential districts (Yirgachefe, Bule and Gedeb) were purposely selected from Gedeo zone. A total of 180 smallholder sheep farmers were selected at random to complete a structured questionnaire that had been pretested. A pairwise ranking tool was used to prioritize ranked data during focus group discussion. Descriptive statistics were generated using SPSS version 26, while indices were computed for the ranked data. Mating happens because most farmers in Gedeo zone (80%) own breeding rams that are mixed and run with ewe flocks. Fifty-two percent of farmers were certain that their breeding rams mate with neighboring ewes. Nearly 70% of farmers prevented unwanted sheep breeding in their flocks by castrating or isolating undesirable rams from the ewe flock. Undesired or old breeding rams were replaced either from the same flock (58.9%) or purchased from local markets (41.1%). Breeding flock selection was common in Gedeo zone, with 97.2% of farmers selecting breeding rams and 93.3% of farmers selecting breeding ewes. Genotype (Index = 0.26) and body conformation (Index = 0.20) were the primary and secondary criteria used to select breeding ewes. Likewise, confirmation (Index = 0.25), genotype (Index = 0.24) and lamb growth rate (Index = 0.19) were the top three criteria when selecting breeding rams. Approximately three-quarters of interviewed farmers culled sheep due to poor body condition (31.8%), old age (28.6%), sickness (22.7%) and sterility (15.6%). Castration of rams was more common in Gedeb (58.3%) and Yirgachefe (55%) districts, and it was done for fattening, controlling unwanted breeding, and improving temperament. The mean selection and castration age of breeding rams were 13.18 and 30.72 months. In general, sheep breeding strategies for Gedeo zone should take into account section preferences and basic traditional sheep breeding practices.

PMID:35679291 | DOI:10.1371/journal.pone.0269263

PLoS One. 2022 Jun 9;17(6):e0269279. doi: 10.1371/journal.pone.0269279. eCollection 2022.

ABSTRACT

INTRODUCTION: Over the past three decades, undernutrition has become a major cause of morbidity and mortality among children under five years globally. Low birth weight has been identified as a risk factor for child morbidity and mortality, especially among children under five years in sub-Saharan Africa. There is, however, a paucity of empirical literature establishing the association between low birth weight and undernutrition in sub-Saharan Africa. We examined the association between birth weight and nutritional status of children under five in sub-Saharan Africa.

METHODS: Our analyses were performed on a weighted sample of 110,497 children under five years from 32 countries in sub-Saharan Africa. Data were obtained from the Demographic and Health Surveys conducted from 2010 to 2019. We reported the prevalence of low birth weight and nutritional status (stunting, wasting, and underweight) for all the 32 countries using percentages. We used multilevel binary logistic regression to examine the association between birth weight and nutritional status (stunting, wasting, and underweight) of the children, controlling for covariates. The results of the regression analyses were presented using adjusted odds ratios (aOR) with 95% confidence intervals. Statistical significance was set at p<0.05.

RESULTS: The prevalence of low birth weight was 5.4%, with the highest (13.1%) and lowest (0.9%) reportedin South Africa and Chad, respectively. The pooled prevalence of wasting, underweight, and stunting were 8.1%, 17.0%, and 31.3%, respectively. Niger had the highest prevalence of wasting (21.5%) and underweight (37.1%), whereas Burundi had the highest prevalence of stunting (51.7%). We found that children with low birth weight were more likely to be stunted [aOR = 1.68, 95% CI = 1.58-1.78], underweight [aOR = 1.82, 95% CI = 1.70-1.94], and wasted [aOR = 1.35, 95% CI = 1.20-1.38] after controlling for covariates.

CONCLUSION: Our study has demonstrated that low birth weight is a key determinant of undernutrition among children under five in sub-Saharan Africa. Policymakers need to give special attention to improving the nutritional status of children under-five years in sub-Saharan Africa by implementing measures aimed at enhancing the weight of children. To accelerate progress towards the achievement of the Sustainable Development Goal 3.2 target of ending preventable deaths of newborns and under-five by 2030, it is imperative for countries in sub-Saharan Africa to intensify interventions aimed at improving maternal and child nutrition. Specific nutrition interventions such as dietary modification counselling should prioritized.

PMID:35679306 | DOI:10.1371/journal.pone.0269279

PLoS One. 2022 Jun 9;17(6):e0268914. doi: 10.1371/journal.pone.0268914. eCollection 2022.

ABSTRACT

White sharks (Carcharodon carcharias) are the largest shark species to display regional endothermy. This capability likely facilitates exploitation of resources beyond thermal tolerance thresholds of potential sympatric competitors as well as sustained elevated swim speeds, but results in increased metabolic costs of adults, which has been documented in different studies. Little, however, is known of the metabolic requirements in free-swimming juveniles of the species, due to their large size at birth and challenges in measuring their oxygen consumption rates in captivity. We used trilateration of positional data from high resolution acoustic-telemetry to derive swim speeds from speed-over-ground calculations for eighteen free-swimming individual juvenile white sharks, and subsequently estimate associated mass-specific oxygen consumption rates as a proxy for field routine metabolic rates. Resulting estimates of mass-specific field routine metabolic rates (368 mg O2 kg-1 h-1 ± 27 mg O2 kg-1 h-1 [mean ± S.D.]) are markedly lower than those reported in sub-adult and adult white sharks by previous studies. We argue that median cruising speeds while aggregating at nearshore nursery habitats (0.6 m s-1 [mean ± S.E = 0.59 ± 0.001], 0.3 TL s-1) are likely a feature of behavioral strategies designed to optimize bioenergetic efficiency, by modulating activity rates in response to environmental temperature profiles to buffer heat loss and maintain homeostasis. Such behavioral strategies more closely resemble those exhibited in ectotherm sharks, than mature conspecifics.

PMID:35679282 | DOI:10.1371/journal.pone.0268914

PLoS Negl Trop Dis. 2022 Jun 9;16(6):e0010441. doi: 10.1371/journal.pntd.0010441. eCollection 2022 Jun.

ABSTRACT

Chikungunya, a mosquito-borne disease, is a growing threat in Brazil, where over 640,000 cases have been reported since 2017. However, there are often long delays between diagnoses of chikungunya cases and their entry in the national monitoring system, leaving policymakers without the up-to-date case count statistics they need. In contrast, weekly data on Google searches for chikungunya is available with no delay. Here, we analyse whether Google search data can help improve rapid estimates of chikungunya case counts in Rio de Janeiro, Brazil. We build on a Bayesian approach suitable for data that is subject to long and varied delays, and find that including Google search data reduces both model error and uncertainty. These improvements are largest during epidemics, which are particularly important periods for policymakers. Including Google search data in chikungunya surveillance systems may therefore help policymakers respond to future epidemics more quickly.

PMID:35679262 | DOI:10.1371/journal.pntd.0010441

PLoS One. 2022 Jun 9;17(6):e0269605. doi: 10.1371/journal.pone.0269605. eCollection 2022.

ABSTRACT

BACKGROUND & OBJECTIVE: Heterozygous familial hypercholesterolemia (FHeH) is important risk factor for premature coronary artery disease (CAD). Strategies for its diagnosis and prevalence have not been well studied in India. We performed healthcare worker-based opportunistic screening to assess feasibility for determining its prevalence.

METHODS: A healthcare worker was trained in use of Dutch Lipid Clinic Network (DLCN) criteria for diagnosis of FHeH. Successive eligible individuals (n = 3000 of 3450 screened) presenting to biochemistry laboratories of two hospitals for blood lipid measurements were evaluated for FHeH. Cascade screening or genetic studies were not performed. Descriptive statistics are reported.

RESULTS: We included 2549 participants (men 1870, women 679) not on statin therapy. Health worker screened 25-30 individuals/day in 6-10 minutes each. The mean age was 46.2±11y. Variables of DLCN criteria were more in women vs men: family history 51.1 vs 35.6%, past CAD 48.2 vs 20.1%, arcus cornealis 1.1 vs 0.3%, tendon xanthoma 0.3 vs 0.1%, and LDL cholesterol 190-249 mg/dl in 8.5 vs 2.4%, 250-329 mg/dl in 0.7 vs 0% and ≥330 mg/dl in 0.3 vs 0% (p<0.01). Definite FHeH (DLCN score >8) was in 15 (0.59%, frequency 1:170) and probable FHeH (score 6-8) in 87 (3.4%, frequency 1:29). The prevalence was significantly greater in women, age <50y and in those with hypertension, diabetes and known CAD.

CONCLUSIONS: Healthcare worker-led opportunistic screening for diagnosis of FHeH using DLCN criteria is feasible in low-resource settings. The results show significant prevalence of clinically detected definite and probable FHeH in the population studied.

PMID:35679249 | DOI:10.1371/journal.pone.0269605

Multivariate Behav Res. 2022 Jun 9:1-21. doi: 10.1080/00273171.2022.2077287. Online ahead of print.

ABSTRACT

Researchers with mediation hypotheses must consider which design to use: within-subject or between-subject? In this paper, I argue that three factors should influence design choice: validity, causality, and statistical power. Threats to validity include carry-over effects, participant awareness, measurement, and more. Causality is a core element of mediation, and the assumptions required for causal inference differ between the two designs. Between-subject designs require more restrictive no-confounder assumptions, but within-subject designs require the assumption of no carry-over effects. Statistical power should be higher in within-subject designs, but the degree and conditions of this advantage are unknown for mediation analysis. A Monte Carlo simulation compares designs under a broad range of sample sizes, effect sizes, and correlations among repeated measurements. The results show within-subject designs require about half the sample size of between-subject designs to detect indirect effects of the same size, but this difference can vary with population parameters. I provide an empirical example and R script for conducting power analysis for within-subject mediation analysis. Researchers interested in conducting mediation analysis should not select within-subject designs merely because of higher power, but they should also consider validity and causality in their decision, both of which can favor between-subject designs.

PMID:35679239 | DOI:10.1080/00273171.2022.2077287