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Nevin Manimala Statistics

Robust group variable screening based on maximum Lq-likelihood estimation

Stat Med. 2021 Oct 17. doi: 10.1002/sim.9212. Online ahead of print.

ABSTRACT

Variable screening plays an important role in ultra-high-dimensional data analysis. Most of the previous analyses have focused on individual predictor screening using marginal correlation or other rank-based techniques. When predictors can be naturally grouped, the structure information should be incorporated while applying variable screening. This study presents a group screening procedure that is based on maximum Lq-likelihood estimation, which is being increasingly used for robust estimation. The proposed method is robust against data contamination, including a heavy-tailed distribution of the response and a mixture of observations from different distributions. The sure screening property is rigorously established. Simulations demonstrate the competitive performance of the proposed method, especially in terms of its robustness against data contamination. Two real data analyses are presented to further illustrate its performance.

PMID:34658050 | DOI:10.1002/sim.9212

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Nevin Manimala Statistics

Barbiturate-related hospitalisations, drug treatment episodes, and deaths in Australia, 2000-2018

Med J Aust. 2021 Oct 17. doi: 10.5694/mja2.51306. Online ahead of print.

ABSTRACT

OBJECTIVES: To determine the characteristics and population rates of barbiturate-related hospitalisations, treatment episodes, and deaths in Australia, 2000-2018.

DESIGN, SETTING: Analysis of national data on barbiturate-related hospitalisations (National Hospital Morbidity Database, 1999-2000 to 2017-18), drug treatment episodes (Alcohol and Other Drug Treatment Services National Minimum Data Set, 2002-03 to 2017-18), and deaths (National Coronial Information System, 2000-01 to 2016-17).

MAIN OUTCOME MEASURES: Population rates directly age-standardised to the 2001 Australian standard population; average annual percentage change (AAPC) in rates estimated by Joinpoint regression.

RESULTS: We identified 1250 barbiturate-related hospitalisations (791 cases of deliberate self-harm [63%]), 993 drug treatment episodes (195 cases with barbiturates as the principal drug of concern [20%]), and 511 deaths during the respective analysis periods. The barbiturate-related hospitalisation rate declined from 0.56 in 1999-2000 to 0.14 per 100 000 population in 2017-18 (AAPC, -6.0%; 95% CI, -7.2% to -4.8%); the declines in hospitalisations related to accidental poisoning (AAPC, -5.8%; 95% CI, -9.1% to -2.4%) and intentional self-harm (AAPC, -5.6%; 95% CI, -6.9% to -4.2%) were each statistically significant. Despite a drop from 0.67 in 2002-03 to 0.23 per 100 000 in 2003-04, the drug treatment episode rate did not decline significantly (AAPC, -6.7%; 95% CI, -16% to +4.0%). The population rate of barbiturate-related deaths increased from 0.07 in 2000-01 to 0.19 per 100 000 population in 2016-17 (AAPC, +9.3%; 95% CI, +6.2-12%); the rate of intentional self-harm deaths increased (AAPC, +11%; 95% CI, +7.4-15%), but not that of accidental deaths (AAPC, -0.3%; 95% CI, -4.1% to +3.8%).

CONCLUSIONS: While prescribing and community use of barbiturates has declined, the population rate of intentional self-harm using barbiturates has increased. The major harm associated with these drugs is now suicide.

PMID:34658038 | DOI:10.5694/mja2.51306

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Nevin Manimala Statistics

Censoring-robust time-dependent receiver operating characteristic curve estimators

Stat Med. 2021 Oct 17. doi: 10.1002/sim.9216. Online ahead of print.

ABSTRACT

Time-dependent receiver operating characteristic curves are often used to evaluate the classification performance of continuous measures when considering time-to-event data. When one is interested in evaluating the predictive performance of multiple covariates, it is common to use the Cox proportional hazards model to obtain risk scores; however, previous work has shown that when the model is mis-specified, the estimand corresponding to the partial likelihood estimator depends on the censoring distribution. In this manuscript, we show that when the risk score model is mis-specified, the AUC will also depend on the censoring distribution, leading to either over- or under-estimation of the risk score’s predictive performance. We propose the use of censoring-robust estimators to remove the dependence on the censoring distribution and provide empirical results supporting the use of censoring-robust risk scores.

PMID:34658036 | DOI:10.1002/sim.9216

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Nevin Manimala Statistics

Virtual reconstruction of orbital floor defects using a statistical shape model

J Anat. 2021 Oct 17. doi: 10.1111/joa.13550. Online ahead of print.

ABSTRACT

PURPOSE: The current standard in reconstructing defects of the orbital floor, by using the concept of mirroring, is time-consuming and ignores the natural asymmetry of the skull. By using a statistical shape model (SSM), the reconstruction can be automatized and improved in accuracy. The present study aims to show the possibilities of the virtual reconstruction of artificial defects of the orbital floor using an SSM and its potentials for clinical implementation.

METHODS: Based on 131 unaffected CT scans of the midface, an SSM was created which contained the shape variability of the orbital floor. Nineteen midface CT scans, that were not included in the SSM, were manually segmented to establish ground truth (control group). Then artificial defects of larger and smaller sizes were created and reconstructed using SSM (Group I) and the gold standard of mirroring (Group II). Eventually, a comparison to the surface of the manual segmentation (control group) was performed.

RESULTS: The proposed method of reconstruction using an SSM leads to more precise reconstruction results, compared with the conventional method of mirroring. Whereas mirroring led to the reconstruction errors of 0.7 mm for small defects and 0.73 mm for large defects, reconstruction using SSM led to deviations of 0.26 mm (small defect) and, respectively, 0.34 mm (large defect).

CONCLUSIONS: The presented approach is an effective and accurate method for reconstructing the orbital floor. In connection with modern computer-aided design and manufacturing, individual patient-specific implants could be produced according to SSM-based reconstructions and could replace current methods using manual bending techniques. By acknowledging the natural asymmetry of the human skull, the SSM-based approach achieves higher accuracy in reconstructing injured orbits.

PMID:34658032 | DOI:10.1111/joa.13550

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Nevin Manimala Statistics

Financial Impacts of the Medicaid Expansion on Community Health Centers

Health Serv Res. 2021 Oct 18. doi: 10.1111/1475-6773.13897. Online ahead of print.

ABSTRACT

OBJECTIVE: To determine the impacts of the Medicaid expansion on revenues, costs, assets and liabilities of federally funded community health centers.

DATA SOURCES: We combined data from the Uniform Data System, Internal Revenue Service non-profit tax returns, and county level characteristics from the Census Bureau. Our final dataset included 5841 center-year observations.

STUDY DESIGN: We used difference-in-differences model to estimate the fiscal impacts of the Medicaid expansion on community health centers. We employed event study models, state specific trend models, and placebo law tests as robustness checks.

DATA COLLECTION METHODS: Not applicable.

PRINCIPAL FINDINGS: On the revenue side, we found a $2.08 million relative increase (p = 0.002) in Medicaid revenues, offset by a $0.44 million decrease (p = 0.015) in total grants among community health centers in expansion states compared to centers in non-expansion states. On the expenditure side, we found a large but not statistically significant $0.98 million relative increase (p = 0.201) in total expenditures among centers in expansion states. Uncompensated care for health centers in expansion states decreased by $1.19 million (p < 0.001) relative to their counterparts in non-expansion states.

CONCLUSIONS: Community health centers in expansion states benefited from the increased, stable revenue stream from Medicaid expansions. While Medicaid revenue increased as a result of the policy, we find no major evidence of substitution away from other revenue lines, with one notable exception (i.e., substitution away from state and local government grants). From a policy perspective, these results are encouraging as the Biden Administration starts to implement the safety-net enhancements from the American Rescue Plan Act of 2021 and as more non-expansion states are considering opting into Medicaid expansions. It is anticipated that these added revenue streams will help to sustain health centers in the delivery of health care services to the underserved population. This article is protected by copyright. All rights reserved.

PMID:34658030 | DOI:10.1111/1475-6773.13897

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Nevin Manimala Statistics

Assessment of exposure to direct oral anticoagulants in elderly hospitalised patients

Br J Haematol. 2021 Oct 17. doi: 10.1111/bjh.17899. Online ahead of print.

ABSTRACT

It is unclear whether elderly patients established on direct oral anticoagulants (DOACs) have greater exposure to these drugs, which could subsequently increase their risk of bleeding. We assessed DOAC exposure and factors affecting it in a real-world elderly cohort of patients. For this, 151 medically stable hospital inpatients (76 established on apixaban, 61 on rivaroxaban, 14 on dabigatran) with a median [interquartile range (IQR)] age of 84 (78-89) years were recruited. Patients provided blood samples for measurement of peak and trough plasma DOAC concentrations. There was up to 48-fold and 13-fold variation in trough and peak plasma drug concentrations respectively. A significantly greater proportion of patients on apixaban had peak plasma drug concentrations within the reported ranges compared to those on either rivaroxaban or dabigatran (82·9% vs. 44·3% vs. 64·3% respectively; P < 0·001). A third of the variability in DOAC plasma concentrations was attributed to the influences of DOAC dosage, renal function and gender. To what extent the observed increases in DOAC exposure in the older patients is the cause of their increased risk of bleeding, which could potentially be ameliorated by dosing titration, requires further investigation.

PMID:34658009 | DOI:10.1111/bjh.17899

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Nevin Manimala Statistics

Depression and Anxiety in Rosacea Patients: A Systematic Review and Meta-Analysis

Dermatol Ther (Heidelb). 2021 Oct 18. doi: 10.1007/s13555-021-00613-w. Online ahead of print.

ABSTRACT

INTRODUCTION: Depression and anxiety are common among people with rosacea. However, the exact magnitude of the prevalence rate and odds ratios (ORs) for depression and anxiety, respectively, in rosacea patients is unclear, and no systematic review or meta-analysis of published data has yet been performed. We therefore performed as systematic review and meta-analysis to determine the prevalence rates and ORs for depression and anxiety in rosacea patients.

METHODS: We performed a systematic search of the PubMed, Embase and Medline databases for all observational studies published up to October 2020 that reported the prevalence rates and ORs for depression and anxiety in patients with rosacea. The primary outcome measures were prevalence rates and ORs for depression and anxiety in patients with rosacea. Heterogeneity across studies was assessed with the I2 statistic. Sources of heterogeneity were explored through subgroup and meta-regression analyses.

RESULTS: A total of 14 studies involving 14,134,021 patients with rosacea were included in the systematic review and meta-analysis. The pooled prevalence of depression was 19.6% (95% confidence interval [CI] 15.0-24.3%) and that of anxiety was 15.6% (95% CI 11.8-19.3%). The prevalence of depression and anxiety was significantly lower in studies using clinical criteria to diagnose depression and anxiety (9.2 and 10.2%, respectively) than in those studies using screening tools (26.2% [P < 0.01] and 22.7% [P = 0.03], respectively). The methodological quality of the included studies greatly contributed to the heterogeneity. Patients with rosacea were more likely to experience depression (OR 2.21, 95% CI 1.79-2.72) and anxiety (OR 2.31, 95% CI 1.56-3.44) than healthy controls.

CONCLUSIONS: This systematic review and meta-analysis indicates that patients with rosacea are at a higher risk of experiencing depression and anxiety. More efforts are warranted to recognize and manage depression and anxiety in patients with rosacea.

PMID:34657997 | DOI:10.1007/s13555-021-00613-w

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Nevin Manimala Statistics

Bark thickness models for oak forests being converted from coppice to high forests in Northwestern Turkey

Environ Monit Assess. 2021 Oct 17;193(11):728. doi: 10.1007/s10661-021-09524-x.

ABSTRACT

The research was carried out in the coppice-originated pure oak stands that are being converted to high forests in northwest Turkey. The main goal of the research was to determine the bark thickness (BT) based on tree variables, such as tree diameter at breast height (DBH), total tree height (H), crown diameter (CD), and age (AGE) of the stem sections taken from a total of 350 trees that were destructively sampled from different sites, different oak species (Quercus petraea, Quercus frainetto, Quercus cerris), and different development stages. Models were developed with stepwise multiple regression analysis to predict BT based on the variables. For all oak species, all models obtained by stepwise multiple regression analysis were found to be significant at p = 0.001 level. In Quercus petraea, only the DBH-dependent model explained the variation in BT at a rate of 73%, estimating with an absolute error rate of 21%. The fit statistics of the models (based on DBH and DBH-H explanatory variables) obtained for Quercus frainetto are very close to each other, and they explained the variation in BT at a rate of 69% and estimated with an error rate of 26%. Models (based on DBH and DBH-H explanatory variables) explain the variation in BT in Turkey oak at a rate of 91%, indicating species-specific results. The models based on only DBH can be used with high accuracy to estimate BT.

PMID:34657980 | DOI:10.1007/s10661-021-09524-x

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Nevin Manimala Statistics

Colonic involvement in acute mesenteric ischemia: prevalence, risk factors, and outcomes

Eur Radiol. 2021 Oct 18. doi: 10.1007/s00330-021-08318-6. Online ahead of print.

ABSTRACT

OBJECTIVES: This study aimed to investigate the prevalence, risk factors, and outcomes of colonic involvement in patients with acute mesenteric ischemia (AMI).

METHODS: CT scans from a prospective cohort of 114 AMI patients treated in an intestinal stroke center between 2009 and 2018 were blindly reviewed by two radiologists. Colon involvement was defined on CT scan by the presence of at least one of the following CT colonic features: wall thickening, pneumatosis, decreased wall enhancement, dilatation, or perforation. In addition, the clinical, biological, and radiological characteristics of patients with and without colonic involvement were compared to identify risk factors for colonic involvement on CT and its impact on morbidity and mortality.

RESULTS: Colonic involvement was identified in 32/114 (28%) patients with AMI, the right colon being more frequently involved (n = 29/32, 91%). Wall thickening (n = 27/32) was the most common CT finding. Occlusion of the inferior mesenteric artery was the only statistically significant risk factor for colonic involvement (35% vs. 15%, p = 0.02). Patients with colonic involvement on CT vs. those without had more frequently transmural colonic necrosis (13% vs. 0%, p = 0.006), short bowel syndrome (16% vs. 4%, p = 0.04), need for long-term parenteral support (19% vs. 5%, p = 0.03), and death during follow-up (22% vs. 10%, p = 0.03).

DISCUSSION: In patients with AMI, colonic involvement is associated with increased morbidity and mortality and should be carefully searched for during initial CT scan assessment.

KEY POINTS: • In a prospective cohort of acute mesenteric ischemia patients from an intestinal stroke center, 28% had an associated colonic involvement on CT. • Colonic involvement on CT most commonly affected the right colon, and the occlusion of the inferior mesenteric artery was the only risk factor. • Colonic involvement on CT was associated with increased morbidity and mortality and should be carefully searched for during initial CT scan assessment.

PMID:34657969 | DOI:10.1007/s00330-021-08318-6

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Nevin Manimala Statistics

Medication overuse headache: The effectivity of iv lidocaine – magnesium

Ideggyogy Sz. 2021 Sep 30;74(9-10):323-328. doi: 10.18071/isz.74.0323.

ABSTRACT

BACKGROUND AND PURPOSE: The detoxification process in medication overuse headache is the most difficult process for the patient. We aimed to investigate the effectiveness of the combination of low dose IV lidocaine and magnesium (100 mg lidocaine and 1.25 mg magnesium) in patients with medication overuse headache during the detoxification process.

METHODS: A total of 30 patients were included in the study; 15 received 24 hours of IV hydration, 15 received 1-hour lidocaine-magnesium infusion at the onset of pain in addition to the 24 hours of IV hydration. Headache severity (numeric rating scale, NRS), attack durations, onset of headache, monthly analgesic/triptan intakes, numbers of monthly headache days data were documented. We evaluated the severity of headache before and after daily treatment of two groups for one week.

RESULTS: When both groups were compared, there was no significant difference in the pre-treatment NRS values, whe-reas, in the group receiving IV lidocaine-magnesium combination, there was a statistically significant decrease in the post-treatment NRS values in the first five days (p <0.05).

CONCLUSION: An 1-hour combined infusion of lidocaine-magnesium may be considered as an alternative option for the patient to have a more quality detoxification process during the hospital stay, so that in parallel to the reduction in the use of multiple treatments (such as neuroleptics, benzodiazepines, antiemetics and opioids) and duration length of stay, the economic costs can also be reduced. The administration of combination will bring fewer side effects compared to their administration separately.

PMID:34657403 | DOI:10.18071/isz.74.0323