Category: Statistics

Scand J Med Sci Sports. 2022 Feb 1. doi: 10.1111/sms.14135. Online ahead of print.

ABSTRACT

OBJECTIVE: To examine the combined effects of cardiorespiratory fitness (CRF) and prediabetes or diabetes on the cardiovascular and non-cardiovascular mortality.

PATIENTS AND METHODS: This prospective study evaluated a population-based cohort of 1562 men aged 42-60 years at baseline (1984-1989). We utilized maximal oxygen uptake (VO_2max ) for assessing aerobic capacity and CRF in the cohort and stratified participants into six groups according to both their glucose status (diabetes, prediabetes or no diabetes) and whether they were below- or above-median VO_2max . Deaths in the cohort were recorded till 31^st Dec 2016. Cox regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI) for cardiovascular and non-cardiovascular mortality. Smoking, alcohol consumption, BMI, blood pressure, cholesterol, diagnosis of ischemic heart disease and socioeconomic status served as covariates in the mortality analyses.

RESULTS: During the follow-up (mean 24.2 years), 341 men died from cardiovascular and 468 men from non-cardiovascular causes. When compared to men with no diabetes and above-median VO_2max , the presence of either diabetes (HR=4.10, 95% CI: 2.27-7.40) or prediabetes (HR=2.10, 95% CI: 1.18-3.73) combined with below-median VO_2max increased the risk of cardiovascular death. Non-cardiovascular mortality was increased by low oxygen uptake in men with prediabetes (HR=2.24, 95% CI: 1.30-3.84), among men with diabetes the increase was not statistically significant (HR=1.99, 95% CI: 0.91-4.32).

CONCLUSION: CRF modifies the risk of death related to prediabetes and diabetes. This highlights the importance of CRF assessment and interventions to support the uptake of regular physical activity among aging men with disturbed glucose metabolism.

PMID:35103994 | DOI:10.1111/sms.14135

Anat Histol Embryol. 2022 Feb 1. doi: 10.1111/ahe.12787. Online ahead of print.

ABSTRACT

Age estimation in adult dogs can be performed by the radiographic measurement of the tooth pulp cavity, but the technique has hardly been described. In this study, the application of measuring pulp/tooth width ratios (P/T ratios) of the maxillary canine teeth was investigated. Pulp and tooth widths were measured at two locations on 166 maxillary canine teeth of the heads of 84 dog cadavers, using digital extraoral lateral oblique open mouth radiographs. The dogs belonged to different breeds and sexes and had a known age between 194 and 1907 days (approximately 6 months – 5 years). Both at the cemento-enamel junction (CE) and the half-height of the tooth, a comparable non-linear regression with age was demonstrated. Measuring at the CE location was less hindered by wear or superimposition. No statistically significant difference according to sex and breed size and no clinically significant difference according to skull type was found. The highest predictable capacity was found in the youngest dogs until the age of 448 days, of which 84.4% of the canine teeth had a P/T ratio above 0.39. Our results demonstrate that measuring P/T ratios of canine teeth can be used in practice to assign dogs to age categories, with the highest accuracy in young adult dogs.

PMID:35104017 | DOI:10.1111/ahe.12787

Eat Weight Disord. 2022 Feb 1. doi: 10.1007/s40519-022-01368-9. Online ahead of print.

ABSTRACT

PURPOSE: Orthorexia nervosa (ON) is an eating behavior where patients obsessively try to reach health through “purity” of food. Narcissism is a personality trait characterized with the self-belief of grandiosity, importance and need of appreciation. Both of these conditions are connected through self-image in way of reaching perfection through health and body image, whereas one of the ways for reaching it is exercising. This cross-sectional study aimed to investigate ON and its possible association with narcissism in fitness center users.

METHODS: The study included 1017 fitness center users and three questionnaires were used for the assessment: general information, ORTO-R and Narcissistic personality inventory-13 (NPI-13).

RESULTS: There was a significant negative correlation (r = – 0.467, p < 0.001) between the ORTO-R score and the NPI-13 score. Comparison of the ORTO-R score between different durations of using a fitness center showed statistically significant differences (H = 134.72, p < 0.001). The subjects who are using the fitness center for less than 1 year have the highest ORTO-R score, while those who are using it 1-3 years have the lowest ORTO-R score. Moreover, multiple linear regression showed that ORTO-R score retained significant association with NPI-13 (β ± SE, – 0.416 ± 0.026, p < 0.001) and the duration of using a fitness center (0.576 ± 0.068, p < 0.001) after model adjustment for age and BMI.

CONCLUSION: These results are implying that fitness center users could possibly be vulnerable of developing ON and that there is a strong association between ON and narcissism in this population. However, future larger-scale longitudinal studies are needed to address these findings.

LEVEL OF EVIDENCE: Level V, cross-sectional survey-based study.

PMID:35103950 | DOI:10.1007/s40519-022-01368-9

Br J Dermatol. 2022 Feb;186(2):e84-e109. doi: 10.1111/bjd.20912.

ABSTRACT

Linked article: Souedi et al. Br J Dermatol 2022; 186:266-273. The sun is the main source of exposure people have to ultraviolet radiation (UVR). Sun exposure has some health benefits but also some adverse effects (for example sunburn and skin cancer). Studies about the link between UVR exposure and long-term health outcomes have used a number of different ways to try and accurately measure how much UVR individuals have been exposed to. We set out to study how accurate three different ways of measuring exposure to UVR were over 6 months: (1) ambient UVR levels, (2) self-reported time spent outdoors, and (3) a statistical formula. The participants in this study were employees who worked either indoors or outdoors in Catalunya – Spain during the summer and winter months. Using a wristwatch with a dosimeter (a device made specifically to measure solar UVR levels) we measured each of the participants UVR levels daily during their working hours. Using a statistical formula, we calculated the daily dose of solar UVR each participant received by including their measured levels (from the dosimeter), the general ambient UVR levels of that day, and self-reported time spent outdoors. We then compared the results. Of our 39 participants, not surprisingly, we noted that the levels of UVR were higher for outdoor workers and during the summer. We discovered that the calculated levels and the self-reported time spent outdoors (methods 2 and 3) were more accurate than measuring general ambient UVR levels (method 1) alone. These results will be helpful to researchers who are deciding which are the best methods to use in future studies about the health effects of UVR exposure.

PMID:35103991 | DOI:10.1111/bjd.20912

Geroscience. 2022 Feb 1. doi: 10.1007/s11357-021-00489-w. Online ahead of print.

ABSTRACT

Missing data are ubiquitous in aging studies. Combining the National Health and Nutrition Examination Survey (NHANES) 2003/2004 and 2005/2006 cross-sectional aging studies (N = 9307), we investigated the effects of both real and simulated missing data on the Frailty Index (FI) and survival analysis, along with several mitigation strategies. We observed distinct block patterns of missing variables in the dataset. These blocks showed significant hazard rate (HR) differences when they were missing versus present, indicating that missingness cannot be simply ignored. Simulations of this patterned missingness produced a bias of 0.0112 ± 0.0008 to the mean FI when missing values were ignored, representing a change in hazard of 1.09 ± 0.01. A similar bias of 0.0106 ± 0.0001 was estimated in the real missingness. Imputation was able to correct the bias using the multivariate imputation by chained equations (MICE) method via the classification and regression tree (CART) prediction model together with rule-based imputation. Using auxiliary variables (CART+Aux) improved the performance of CART. Well-performing imputation models, especially CART+Aux, were able to increase the FI predictive power and the reliability of the HR estimates. In contrast, the default MICE models, predictive mean matching/logistic regression (PMM/logreg), caused even stronger biases to the FI. Our results demonstrate that calibration of the FI as a mortality predictor depends on how missing data are handled. Ignoring missing values when calculating the FI may be an acceptable strategy for clinical settings where the FI is used as a rough predictor of adverse outcomes. Where the FI is to be compared across studies or populations, judicious imputation – cognizant of the risks carried by poor imputation – should be used to ensure reliability and precision of statistical estimates and conclusions.

PMID:35103915 | DOI:10.1007/s11357-021-00489-w

Psychometrika. 2022 Feb 1. doi: 10.1007/s11336-021-09834-6. Online ahead of print.

ABSTRACT

Equal parameter estimates across subgroups is a substantial requirement of statistical tests. Ignoring subgroup differences poses a threat to study replicability, model specification, and theory development. Structural change tests are a powerful statistical technique to assess parameter invariance. A core element of those tests is the empirical fluctuation process. In the case of parameter invariance, the fluctuation process asymptotically follows a Brownian bridge. This asymptotic assumption further provides the basis for inference. However, the empirical fluctuation process does not follow a Brownian bridge in small samples, and this situation is amplified in large psychometric models. Therefore, common methods of obtaining the sampling distribution are invalid and the structural change test becomes conservative. We discuss an alternative solution to obtaining the sampling distribution-permutation approaches. Permutation approaches estimate the sampling distribution through resampling of the dataset, avoiding distributional assumptions. Hereby, the tests power are improved. We conclude that the permutation alternative is superior to standard asymptotic approximations of the sampling distribution.

PMID:35103931 | DOI:10.1007/s11336-021-09834-6

J Neurooncol. 2022 Feb 1. doi: 10.1007/s11060-022-03955-3. Online ahead of print.

ABSTRACT

BACKGROUND: MGMT promoter methylation has been associated with favorable prognosis and survival outcomes in patients with glioblastoma and WHO grade III glioma. However, the effects of promoter methylation of MGMT in patients with WHO grade II gliomas have not been established. The purpose of the current study is to evaluate the prognostic impact and predictive values of MGMT methylation in patients with grade II glioma.

METHODS: The National Cancer Database (NCDB) was queried (2004-2016) for patients with newly diagnosed grade II glioma. Demographics and clinical characteristics of these patients were examined. Statistics included Kaplan-Meier overall survival (OS) analysis alongside Cox proportional hazards modeling.

RESULTS: A total of 11,223 patients met the selection criteria; 1252 patients (11%) had MGMT testing. Of the patients who had MGMT testing, 58.5% were MGMT methylated (mMGMT), and 43.5% were MGMT unmethylated (uMGMT). mMGMT patients had greater median overall survival (77.3 months) than both uMGMT patients (42.6 months) and patients with no MGMT status reported (61.9 months (p < 0.001 for both). mMGMT was also associated with improved OS, when compared to patients with uMGMT, for patients receiving adjuvant chemoradiation or adjuvant radiation therapy.

CONCLUSIONS: This is the largest study to date demonstrating both the prognostic and predictive impact of MGMT methylation on patients with grade II glioma. The current results show that mMGMT is a prognostic factor and possibly a predictive biomarker for grade II glioma patients. MGMT methylation status can be used to determine and stratify patients by risk levels, and thus select patients for treatment intensification.

IMPORTANCE OF STUDY: The present study is the largest to date examining the prognostic and predictive significance of MGMT methylation (mMGMT) in patients with WHO grade II glioma. The results suggest that mMGMT is prognostic with increasing overall survival rates for patients with mMGMT compared to uMGMT patients. The results also suggest that mMGMT is predictive as shown by improved overall survival in patients receiving gross total resection, adjuvant chemoradiation or adjuvant radiation therapy, but no difference was observed in patients receiving adjuvant chemotherapy or no adjuvant treatment.

PMID:35103907 | DOI:10.1007/s11060-022-03955-3

Int J Cardiovasc Imaging. 2022 Feb 1. doi: 10.1007/s10554-022-02541-y. Online ahead of print.

ABSTRACT

Previous reports suggested that poor pulmonary function was associated with increased arterial elastance (Ea) in patients with chronic obstructive pulmonary disease and systemic sclerosis. The mechanisms connecting pulmonary function and Ea have not yet been accurately studied in patients with idiopathic pulmonary fibrosis (IPF). The present study was designed to assess Ea in IPF patients without chronic severe pulmonary hypertension and to determine its prognostic role over a medium-term follow-up. This retrospective study included 60 consecutive patients with mild-to-moderate IPF (73.8 ± 6.6 years, 75% males) and 60 controls matched by age, sex and cardiovascular risk factors. All patients underwent physical examination, spirometry, blood tests, modified Haller index (MHI, chest transverse diameter over the distance between sternum and spine) assessment, conventional transthoracic echocardiography implemented with speckle tracking analysis of left atrial positive global strain (LA-GSA+ ) and finally carotid Doppler ultrasonography, at basal evaluation. The effective arterial elastance index (EaI) was calculated as the ratio of end-systolic pressure to stroke volume index. During follow-up period, we evaluated the composite endpoint of (1) pulmonary or cardiovascular hospitalizations; (2) all-cause mortality. At baseline, EaI was significantly higher in IPF patients than controls (4.1 ± 1.3 vs 3.5 ± 1.0 mmHg/ml/m², p = 0.01). EaI was strongly correlated to the following variables: C-reactive protein (CRP) (r = 0.86), forced vital capacity (FVC) (r = – 0.91), E/e’ ratio (r = 0.91), LA-GSA+ (r = – 0.92), common carotid artery-cross sectional area (CCA-CSA) (r = 0.89) and MHI (r = 0.86), in IPF patients. Mean follow-up time was 2.4 ± 1.3 years. During follow-up, 12 patients died and 17 were hospitalized due to major adverse clinical events. At univariate Cox analysis, CRP (HR 1.51, 95% CI 1.25-1.82), FVC (HR 0.88, 95% CI 0.85-0.91), LA-GSA+ (HR 0.85, 95% CI 0.77-0.94), CCA-CSA (HR 1.12, 95% CI 1.03-1.22) and EaI (HR 2.43, 95% CI 1.75-3.37) were significantly associated with outcome. At multivariate Cox analysis, only EaI (HR 1.60, 95% CI 1.03-2.50) retained statistical significance. An EaI ≥ 4 mmHg/ml/m² showed 100% sensitivity and 99.4% specificity for predicting outcome (AUC = 0.98). In patients with mild-to-moderate IPF, an EaI ≥ 4 mmHg/ml/m² is a negative prognostic factor over a medium-term follow-up.

PMID:35103898 | DOI:10.1007/s10554-022-02541-y

Tech Coloproctol. 2022 Feb 1. doi: 10.1007/s10151-022-02582-4. Online ahead of print.

ABSTRACT

BACKGROUND: Surgical management of anal fistulas in Crohn’s disease (CD) is associated with high failure rates, and treatment options are limited due to ongoing proctitis, multiple tracts, and concern for incontinence and non-healing wounds. The aim of this study was to investigate the healing rate of ligation of the inters-sphincteric fistula tract (LIFT) for anal fistulas in Crohn’s disease and identify prognostic factors for healing.

METHODS: This prospective analysis compared long-term healing rates of CD patients undergoing LIFT for anal fistulas. Consecutive patients with CD who underwent LIFT procedure at our institution, in the period from March 2012 to September 2019 were included. The main outcome was anal fistula healing rate.

RESULTS: The study cohort of 46 patients (mean age of 34.2 ± 13.0 years, 18 (40%) males). After a mean follow-up time of 33 ± 28 months, fistula healing was seen in 30 (65%) patients. A total of 8 patients were noted to have inter-sphincteric recurrence and 8 patients had trans-sphincteric recurrence. Smoking at the time of surgery was significantly associated with LIFT failure (HR 3.18, 95% CI 1.18-8.61, p = 0.02). Other factors, such as age, sex, race, disease duration and location, type of fistula history of proctitis, preoperatively use of biologics or a seton, and previous repair attempts, did not appear to influence LIFT healing. Although not statistically significant, there was a trend toward increase in failure among patients with active proctitis at the time of surgery (HR 1.97, 95% CI 0.71-5.42, p = 0.19).

CONCLUSION: Our increasing experience with LIFT for anal fistula in CD demonstrates a higher rate of healing (65%) than previously reported (48%). Smoking appears to negatively influence healing of LIFT in CD.

PMID:35103901 | DOI:10.1007/s10151-022-02582-4

Health Care Manag Sci. 2022 Feb 1. doi: 10.1007/s10729-021-09589-7. Online ahead of print.

ABSTRACT

Measuring the relative efficiency of a finite fixed set of service-producing units (hospitals, state services, libraries, banks,…) is an important purpose of Data Envelopment Analysis (DEA). We illustrate an innovative way to measure this efficiency using stochastic indexes of the quality from these services. The indexes obtained from the opinion-satisfaction of the customers are estimators, from the statistical view point, of the quality of the service received (outputs); while, the quality of the offered service is estimated with opinion-satisfaction indexes of service providers (inputs). The estimation of these indicators is only possible by asking a customer and provider sample, in each service, through surveys. The technical efficiency score, obtained using the classic DEA models and estimated quality indicators, is an estimator of the unknown population efficiency that would be obtained if in each one of the services, interviews from all their customers and all their providers were available. With the object of achieving the best precision in the estimate, we propose results to determine the sample size of customers and providers needed so that with their answers can achieve a fixed accuracy in the estimation of the population efficiency of these service-producing units through the use of a novel one bootstrap confidence interval. Using this bootstrap methodology and quality opinion indexes obtained from two surveys, one of doctors and another of patients, we analyze the efficiency in the health care system of Spain.

PMID:35103882 | DOI:10.1007/s10729-021-09589-7