Category: Statistics

BMC Oral Health. 2026 Jan 8. doi: 10.1186/s12903-025-07634-3. Online ahead of print.

ABSTRACT

BACKGROUND: With the rapid advancement of digital technologies, digital intraoral scanning offers potential advantages for post-and-core impressions. However, its accuracy in relation to the complete spectrum of clinically relevant post space diameters, particularly smaller conservative preparations, requires comprehensive evaluation. This in vitro study aimed to systematically assess the accuracy of direct digital impressions compared to conventional impressions across four diameters and varying depths.

METHODS: Forty extracted single-rooted teeth were divided into four groups (n = 10/group) based on post space diameter: 1.0, 1.5, 2.0, and 2.5 mm. Each specimen was scanned using an intraoral scanner (TRIOS 5). Silicone impressions scanned with an extraoral scanner served as the reference. Root mean square (RMS) deviations were analyzed at four depths (1.65, 5.0, 7.0, 9.0 mm). Statistical analysis employed linear mixed-effects models.

RESULTS: The scanner completely failed to capture data for the 1.0 mm diameter at depths ≥ 7 mm and for the 1.5 mm diameter at 9 mm. A significant diameter-by-depth interaction was found (p < 0.001). For diameters ≥ 1.5 mm and depths ≤ 7 mm, accuracy was clinically acceptable. At the 9 mm depth, the 2.0 mm and diameter group showed significantly higher deviation and critically high variability (135.0 ± 79.5 μm, CV 59.0%), while the 2.5 mm group maintained superior and more reliable accuracy (41.4 ± 28.8 μm).

CONCLUSIONS: Direct intraoral scanning is a viable option for post spaces with a diameter ≥ 1.5 mm and depth ≤ 7 mm. Its application is strictly limited in narrow canals (≤ 1.5 mm). For deep preparations (9 mm), a minimum diameter of 2.0 mm allows data capture but with poor reliability, whereas a diameter ≥ 2.5 mm ensures acceptable and predictable accuracy. Clinical adoption requires careful consideration of these diameter- and depth-dependent performance boundaries.

PMID:41501705 | DOI:10.1186/s12903-025-07634-3

BMC Public Health. 2026 Jan 7. doi: 10.1186/s12889-025-26034-4. Online ahead of print.

ABSTRACT

BACKGROUND: Changes in movement behaviors – physical activity (PA), sedentary behavior, and sleep patterns – across preconception, pregnancy, and postpartum are associated with maternal and child health but remain understudied. Longitudinal accelerometer-measured data, including weekday-weekend differences, are lacking. Understanding these patterns is essential for developing targeted interventions that account for lifestyle variations. We investigated longitudinal changes in PA, sedentary behavior, and sleep patterns throughout preconception, pregnancy, and postpartum using prospectively collected accelerometry data.

METHODS: In a Singapore prospective preconception cohort, women aged 18-45 wore an accelerometer on their non-dominant wrist for seven days during preconception (within one year of planned conception), mid-pregnancy (24-28 weeks), and 12-month postpartum. Valid data required measurements at all three or at least two consecutive timepoints (preconception-pregnancy or pregnancy-postpartum). Changes in PA (vigorous-, moderate-, and light-intensity), sedentary behavior, and sleep were analyzed using generalized estimating equations.

RESULTS: Among 139 women (mean age: 30.8 years), most were under/normal weight (61.9%), Chinese (83.5%), had undergraduate education (59.0%), were employed (88.5%), and nulliparous (65.5%). Moderate- and vigorous-intensity PA decreased from preconception to mid-pregnancy, with vigorous-intensity PA remaining low postpartum, while moderate-intensity PA rebounded (daily mean [95% confidence interval] vigorous: 4.1 [2.8-5.4)], 1.7 [0-4.2], and 1.8 [0-5.0] min/day; moderate: 88.2 [82.8-93.5], 68.7 [58.6-78.7], and 90.2 [77.7-102.7] min/day, respectively). Light-intensity PA remained consistent from preconception to mid-pregnancy but increased postpartum (301.5 [289.6-313.5], 298.3 [273.1-323.5], and 340.1 [305.9-374.5] min/day, respectively). Sedentary behavior rose mid-pregnancy but decreased postpartum (618.2 [603.4-633.1], 639.6 [607.6-671.5], and 597.1 [553.5-640.7] min/day, respectively). Sleep duration remained stable from preconception to mid-pregnancy until postpartum, when it decreased (428.9 [420.6-437.3], 432.2 [412.2-452.1], and 408.4 [387.2-429.6] min/day, respectively). Moderate-/vigorous-intensity PA showed no weekday/weekend differences (daily percentage range, moderate: 4.7-6.6%; vigorous: 0.1-0.3%). Women engaged in less light-intensity PA on weekdays during mid-pregnancy and postpartum (weekdays: 20.5-23.2% versus weekends: 21.3-24.8%). Weekends showed lower sedentary behavior (weekdays: 42.5-45.4% versus weekends: 38.5-42.1%) and longer sleep duration (weekdays: 27.8-29.3% versus weekends: 29.8-32.0%) across all timepoints.

CONCLUSIONS: Sustained moderate- and vigorous-intensity PA from preconception through postpartum should be promoted, particularly vigorous-intensity PA recovery postpartum. Light-intensity PA, which increased postpartum, could be leveraged to reduce sedentary behavior, especially on weekdays. Given postpartum sleep decline, strategies to support maternal sleep, particularly on weekdays, are needed.

CLINICAL TRIAL INFORMATION: ClinicalTrials.gov, NCT03531658 (registered May 22, 2018).

PMID:41501702 | DOI:10.1186/s12889-025-26034-4

BMC Public Health. 2026 Jan 7. doi: 10.1186/s12889-025-26031-7. Online ahead of print.

NO ABSTRACT

PMID:41501701 | DOI:10.1186/s12889-025-26031-7

BMC Med Res Methodol. 2026 Jan 7. doi: 10.1186/s12874-025-02738-4. Online ahead of print.

ABSTRACT

BACKGROUND: Popularized in the 1980s, N-of-1 trials have emerged as a useful study design to assess the effects of interventions in single individuals. This study design consists of observing outcomes over time for the same individual under periods of exposure to an intervention and a comparator. Despite the simple idea, N-of-1 trials can require strong assumptions in the analysis phase to identify and estimate causal effects. As an illustrative example, we present an N-of-1 trial aiming at assessing the effect of alcohol abstinence on mood.

METHODS: The N-of-1 trial participant decided to join a month-long nationwide alcohol abstinence campaign and was interested in the effects of alcohol abstinence on his mood. Every eight hours, the participant collected data about his own mood levels, number of alcohol units consumed, and social interactions, before, during, and after the alcohol abstinence period. Mood levels were measured using a 5-point Likert scale ranging from -2 to 2. To analyze the N-of-1 trial data, we relied on an explicit causal framework and made precise assumptions about the data generating process. We used a g-computation algorithm to estimate, for each time point, the individual-specific difference between the expected mood outcomes under the “always abstain from alcohol” intervention and “always drinking as usual” comparator.

RESULTS: Overall, 264 time points were recorded, 171 under no intervention, and 93 during the intervention (alcohol abstinence) period. After adjusting for the other time-varying causes of mood, no statistically significant effect of alcohol units on mood level was found for measurements at the same time point; however, the number of alcohol units reported had a statistically significant negative effect on mood levels at the subsequent time point. The mean of the individual-specific average treatment effects across the entire study period was 0.05 (95%CI: -0.06, 0.15).

CONCLUSIONS: N-of-1 trials can be truly individual-centric studies, tailored to the needs and preferences of the participants. Analyzing data from N-of-1 trials can be complex, and the use of a causal framework can help inform the analyses.

PMID:41501684 | DOI:10.1186/s12874-025-02738-4

BMC Pediatr. 2026 Jan 8. doi: 10.1186/s12887-025-06480-0. Online ahead of print.

ABSTRACT

INTRODUCTION: Although the risk factors of neonatal mortality are currently known, it was necessary to know the risk factors of mortality in neonatal preterm birth. The present study was conducted to find and investigate the potential maternal, fetal and neonatal risk factors of neonatal mortality among the cases of preterm birth.

METHODS: A retrospective cohort study was conducted with a secondary analysis of existing data of a national registry. All premature infants born in Iran from March 21^st 2019 to March 21^st 2020 were included in the study using census. Mixed model logistic regression was used to identify the potential risk and protecting factors from a selected groups of the variables of the national registry with reporting odds ratio (OR) and 95% confidence interval (CI).

RESULTS: A total of 120,688 cases of preterm labor were studied with GA in the range of 22-36 weeks. A total of 5458 neonatal deaths (4.52% of total cases) were recorded. The most effective protecting factor was increased gestational age (GA) (adjusted OR = 0.664 per week, 95% CI: 0.658-0.669). The risk factors remained in the multivariable modeling were maternal hypertension, eclampsia / preeclampsia, addiction, placental abruption, meconium staining, impaired fetal heart rate, previous neonatal death, intrauterine growth restriction, lack of corticosteroid administration, rural and nomadic residency, cesarean delivery, malformation, public hospital (vs. private), and out-of-hospital delivery (P < 0.1). The protecting factors remained in the multivariable modeling were gestational diabetes mellitus, premature rupture of membrane for more than 18 h, female sex, GA, and mother age (P < 0.1).

CONCLUSION: The present study showed that many maternal and neonatal related variables were potential risk and protecting factors of neonatal death among the preterm birth neonates. The main predictor of the outcome was GA, and using corticosteroid before birth was a modifiable protecting factor.

PMID:41501678 | DOI:10.1186/s12887-025-06480-0

BMC Geriatr. 2026 Jan 8. doi: 10.1186/s12877-026-06971-4. Online ahead of print.

ABSTRACT

BACKGROUND: Although physical frailty has long been recognized as a clinical condition, it has only recently gained attention in Bangladesh. This growing interest reflects the country’s increasing focus on the health challenges faced by its aging population. This study examined the prevalence of physical frailty and its association with cognitive impairment among older adults.

METHODS: The study used a cross-sectional design conducted among 540 older adults aged 65 and above using a multistage sampling technique. Physical frailty status was assessed using the Fried frailty phenotype, and cognitive function was measured with the 30-item Mini-Mental State Examination.

RESULTS: Across two districts, 60% of participants were classified as frail, and 33% were classified as pre-frail. Significant demographic differences were observed across frailty categories, including age, gender, marital status, net monthly income level, and smoking history (p < 0.001). Multinomial logistic regression analyses indicated that several demographic and clinical factors were associated with cognitive impairment, including gender, education, household income, and multimorbidity. Higher household income (> 60,000 Bangladeshi Taka [BDT] per month) was associated with lower odds of severe cognitive impairment (OR = 0.14, 95% CI = 0.04, 0.45). Regular visits from family or friends showed a suggestive association with lower odds of cognitive impairment (OR = 0.59, 95% CI = 0.03, 1.54), although this association did not reach statistical significance at the 0.05 level. Cognitive function tended to be lower among frail participants aged 81 and above, with the lowest observed scores.

CONCLUSION: The findings demonstrate a significant association between physical frailty and cognitive impairment among older adults in Bangladesh, emphasizing the role of social determinants in shaping these outcomes. The results highlight the need for targeted interventions and policy strategies addressing these determinants to promote healthy aging and mitigate cognitive decline in this population.

PMID:41501676 | DOI:10.1186/s12877-026-06971-4

BMC Pregnancy Childbirth. 2026 Jan 8. doi: 10.1186/s12884-025-08618-5. Online ahead of print.

ABSTRACT

OBJECTIVE: To investigate serum xenopsin-related peptide (XRP) -1 levels in women with hyperemesis gravidarum (HEG) from the onset of pregnancy until the end of week 14.

MATERIALS AND METHODS: This cross-sectional study was conducted at the Antalya Training and Research Hospital Obstetrics Clinic, Türkiye, between July and December 2024. Forty-five pregnant diagnosed with HEG and 45 healthy pregnant were included. Venous blood samples for the XRP-1 test were collected from pregnant women and the collected serum samples were stored at -80 degrees until the day of analysis.

RESULTS: Significant differences were observed between the HEG and healthy groups in terms of serum thyroid-stimulating hormone (1.86 ± 0.54 vs. 1.38 ± 0.67, respectively, p = 0.027), potassium (3.84 ± 0.45 vs. 3.58 ± 0.60, p = 0.010), and XRP-1 (4.33 ± 1.66 vs. 2.38 ± 1.32, p < 0.001) values. At receiver operating characteristic analysis, the area under the curve (AUC: 0.824) was statistically significant for serum XRP-1 (p < 0.001), with a cut-off value of ≥ 2.42 [95% confidence interval 0.731-0.917, 82.2% sensitivity, and 80.0% specificity]. The positive predictive value of serum XRP-1 was 80.0% and the negative predictive value was 81.0%.

CONCLUSION(S): This study suggests that serum XRP-1 levels are elevated in HEG. Further studies are now needed to validate these findings.

PMID:41501674 | DOI:10.1186/s12884-025-08618-5

BMC Med Res Methodol. 2026 Jan 8. doi: 10.1186/s12874-025-02751-7. Online ahead of print.

ABSTRACT

INTRODUCTION AND OBJECTIVES: Over recent decades, the exponential growth of data, especially in healthcare, has necessitated advanced analytical methods. Conventional machine learning algorithms often assume independence among data points, limiting their effectiveness with longitudinal and hierarchical data. This study introduces a novel algorithm called GMEXGBoost, a methodological extension of generalized mixed-effects models that leverages the boosting framework of XGBoost for estimating fixed effects while simultaneously accounting for random effects. The innovation lies in GMEXGBoost’s ability to explicitly incorporate data correlations while retaining the predictive power of boosted trees.

METHODS: The GMEXGBoost model was evaluated through extensive simulations and a real-world cohort study, benchmarking against GLMM, GLMMTree, GMERF, and XGBoost. Also, its performance was assessed using predictive mean absolute deviation (PMAD), predictive misclassification rate (PMCR), sensitivity, specificity, accuracy, and AUC. Simulation analyses were conducted using multiple synthetic datasets, each comprising training and testing groups with varying effect structures, including random intercepts and slopes. All computations were performed in RStudio(version 2023.06.0).

RESULTS: Our results indicate that while XGBoost achieved the lowest average errors across most scenarios, GMEXGBoost consistently demonstrated superior stability and accuracy when random-effect variance was large or correlations were strong. Also, in real data, GMEXGBoost outperformed other models in terms of the performance metrics.

CONCLUSION: The GMEXGBoost algorithm, by combining the estimates of the GLMM and XGBoost models, leverages the capabilities of both and delivers improved performance in complex problems. Although it is not universally superior, but demonstrates clear advantages in the analysis of hierarchical and longitudinal datasets with strong correlations. These properties make it a valuable tool for decision-making in healthcare and other domains that involve complex, structured data.

PMID:41501655 | DOI:10.1186/s12874-025-02751-7

Br J Math Stat Psychol. 2026 Jan 7. doi: 10.1111/bmsp.70029. Online ahead of print.

ABSTRACT

Although individuals may exhibit both gradual and abrupt changes in their dynamic properties as shaped by both slowly accumulating influences and acute events, existing statistical frameworks offer limited capacity for the simultaneous detection and representation of these distinct change patterns. We propose a Bayesian regime-switching (RS) modelling framework and an entropy measure adapted from the frequentist framework to facilitate simultaneous representation and testing of postulates of gradual and abrupt changes. Results from Monte Carlo simulation studies indicated that using a combination of entropy and information criterion measures such as the Bayesian information criterion was consistently most effective at facilitating the selection of the best-fitting model across varying magnitudes of abrupt changes. We found that slight lower entropy thresholds may be helpful in facilitating the selection of longitudinal models with RS properties as this class of models tended to yield lower entropy values than conventional thresholds for reliable classification in cross-sectional mixture models-even under satisfactory parameter recovery and classification results. We fitted the proposed models and other candidate models to the data collected from an intervention study on the psychological well-being (PWB) of college-attending early adults. Results suggested abrupt, regime-related transitions in the intra-individual variability levels of PWB dynamics among some participants following the intervention period. Practical usage of the entropy measure in conjunction with other model selection measures, and guidelines to enhance simultaneous detection of true abrupt and gradual changes are discussed.

PMID:41501619 | DOI:10.1111/bmsp.70029

Ann Otol Rhinol Laryngol. 2026 Jan 7:34894251401132. doi: 10.1177/00034894251401132. Online ahead of print.

ABSTRACT

OBJECTIVE: To assess the effect of rhinophototherapy (RPT) on nasal mucosa and inflammatory cells in allergic rhinitis compared to intranasal corticosteroids (INCS).

METHODS: Adult patients (≥18 years) with newly diagnosed perennial allergic rhinitis (AR) were randomly divided into 2 groups, RPT and INCS. Treatment was administered for 2 weeks. Primary outcome was evaluation of the inflammatory cells and mucosal damage via inferior turbinate biopsy, performed post-treatment. Secondary outcomes measured were visual analogue score (VAS) of clinical symptoms (overall, runny nose, sneezing, nasal block, nasal itchiness and ocular itchiness) and nasal patency using rhinomanometry and peak nasal inspiratory flow (PNIF).

RESULTS: Thirty-five patients were included, with 18 patients randomized into RPT and 17 patients into INCS. The mean age of patients was 31.3 ± 9.6 (range: 19-57). There was no statistically significant difference observed in terms of inflammatory cells in both groups. Similarly, both groups had no differences in mucosal damage parameters. Patients in RPT group showed statistically significant improvement for overall and specific symptoms VAS score (P < 0.05). Comparing both groups, patients using INCS reported bigger effect size for overall VAS score and specific VAS score for runny nose, sneezing, nasal and eye itchiness. Both groups showed improvement in PNIF reading post-treatment although only RPT group showed statistical significance (P = .015). In terms of rhinomanometry, both groups showed significant improvement in post-treatment nasal flow rate (P < .05). There was decrease in total nasal resistance observed in both groups, albeit with RPT being statistically significant (P = .004). There were no adverse events reported in both groups.

CONCLUSION: There is no significant difference in inflammatory cells of inferior turbinate mucosa and mucosal damage between RPT and INCS. RPT is a safe and suitable short-term alternative (2 weeks) for AR patients who are contraindicated for or unable to tolerate INCS.

CLINICAL TRIAL NUMBER: The study was registered with ClinicalTrials.gov with the ID: NCT05919316.

PMID:41501617 | DOI:10.1177/00034894251401132