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Nevin Manimala Statistics

The number needed to treat adjusted for explanatory variables in regression and survival analysis: Theory and application

Stat Med. 2022 Apr 26. doi: 10.1002/sim.9418. Online ahead of print.

ABSTRACT

The number needed to treat (NNT) is an efficacy index commonly used in randomized clinical trials. The NNT is the average number of treated patients for each undesirable patient outcome, for example, death, prevented by the treatment. We introduce a systematic theoretically-based framework to model and estimate the conditional and the harmonic mean NNT in the presence of explanatory variables, in various models with dichotomous and nondichotomous outcomes. The conditional NNT is illustrated in a series of four primary examples; logistic regression, linear regression, Kaplan-Meier estimation, and Cox regression models. Also, we establish and prove mathematically the exact relationship between the conditional and the harmonic mean NNT in the presence of explanatory variables. We introduce four different methods to calculate asymptotically-correct confidence intervals for both indices. Finally, we implemented a simulation study to provide numerical demonstrations of the aforementioned theoretical results and the four examples. Numerical analysis showed that the parametric estimators of the NNT with nonparametric bootstrap-based confidence intervals outperformed other examined combinations in most settings. An R package and a web application have been developed and made available online to calculate the conditional and the harmonic mean NNTs with their corresponding confidence intervals.

PMID:35472818 | DOI:10.1002/sim.9418

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Nevin Manimala Statistics

Differences in Mean Values and Variance in Quantitative Analyses of Foveal OCTA Imaging

Klin Monbl Augenheilkd. 2022 Apr;239(4):513-517. doi: 10.1055/a-1766-7268. Epub 2022 Apr 26.

ABSTRACT

PURPOSE: Multiple approaches for quantifying parameters such as vessel density (VD) and vessel length density (VLD) in optical coherence tomography angiography (OCTA) en-face segmentations are currently available. While it is common knowledge that data gathered from different methods should not be directly compared to each other, a comparison of the different methods can help to further the understanding of differences between different methods of measurement. Here we compare a common method of semiautomatically quantifying VD and VLD with an automated method supplied by the manufacturer of an OCTA device and report on differences in performance in order to probe for and highlight differences in values gathered by both methods.

METHODS: OCTA was performed using the swept source PLEX Elite 9000 device, software version 2.0.1.47652 (Carl Zeiss Meditec Inc., Dublin, CA, USA). Scans of 3 mm × 3 mm from healthy volunteers centred on the fovea were acquired by a well-trained certified ophthalmologist. Scans with a signal strength of 8 out of 10 or higher were included. Quantitative parameters of the 3 mm × 3 mm cube scans were automatically generated and segmented into superficial capillary plexus (SCP) and deep capillary plexus (DCP) layers using layer segmentation produced by the instrument software and prototype analysis VD quantification software (Macular Density v.0.7.1, ARI Network Hub, Carl Zeiss Meditec Inc., Dublin, CA, USA) supplied by the manufacturer. An alternative approach of quantitative analysis of VD and VLD was performed manually with ImageJ (National Institutes of Health, Bethesda, Maryland, USA), as previously reported. VD was assessed as the ratio of the retinal area occupied by vessels. VDL was measured as the total length of the skeletonised vessels using 1-pixel centre line extraction of the blood vessels.

RESULTS: We report differences in standard deviation (SD) in OCTA parameters obtained using different methods. The standard deviation of VD and VLD measurements was statistically significantly different in VD of 3 mm × 3 mm DCP (p = 0.009), VLD of 3 mm × 3 mm SCP (p = 0.000), and VLD of 3 mm × 3 mm DCP (p = 0.021). No statistically significant differences were found in VD of 3 mm × 3 mm SCP (p = 0.128) or VLD of 3 mm × 3 mm SCP (p = 0.107).

CONCLUSIONS: As expected, we were able to demonstrate significant differences in quantitative OCTA parameters gathered from the same images using different methods of quantification. Values gathered using different methods are not interchangeable. In scientific studies and in situations where long-term follow-up is necessary, the same device and the same method of quantification should be used to maintain retrospective comparability of measurements.

PMID:35472795 | DOI:10.1055/a-1766-7268

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Nevin Manimala Statistics

“Treat-and-Extend” Regimen for Exudative Age-Related Macular Degeneration: A Two-Year Retrospective Follow-up Study

Klin Monbl Augenheilkd. 2022 Apr;239(4):494-499. doi: 10.1055/a-1770-4037. Epub 2022 Apr 26.

ABSTRACT

BACKGROUND: After the introduction of a “treat-and-extend” regimen (T&E) with aflibercept for exudative age-related macular degeneration, naive eyes were compared with eyes pretreated with a “pro re nata” scheme (PRN).

PATIENTS AND METHODS: The Ethics Committee of Eastern Switzerland approved the retrospective single-centre study (EKOS20/084, project ID: 2020-01193). The study included 342 eyes of 303 patients newly treated with or switched to T&E between January 2018 and March 2018 at the Eye Clinic of the Cantonal Hospital St. Gallen. The gender distribution of the treated eyes was 63.5% (n = 217) female and 36.5% (n = 125) male. The mean age was 81.6 years (SD = 8.6 years). The collective was divided into three groups: 1) naive, untreated eyes (n = 92), 2) eyes with ≤ 6 previous treatments with PRN (n = 37), 3) eyes with > 6 previous treatments with PRN (n = 213). The following parameters were analysed up to December 2019: the evolution of visual acuity, the number of intravitreal injections, the number of recurrences, the duration of the follow-up, the dropout rate, and the duration of the last treatment interval.

RESULTS: During the observation period, group 1 showed a statistically significant improvement in visual acuity of + 1.5 ETDRS, while groups 2 and 3 showed a decrease in visual acuity of – 2.9 and – 3.7 ETDRS, respectively. Group 1 had better development of visual acuity than groups 2 and 3 (p = 0.005), while groups 2 and 3 were not significantly different (p = 0.92). The other parameters examined in the three groups did not differ significantly between groups.

CONCLUSIONS: Treatment with aflibercept in T&E shows significantly better visual acuity in naive eyes than in eyes pretreated with PRN.

PMID:35472793 | DOI:10.1055/a-1770-4037

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Nevin Manimala Statistics

Structural, Microvascular, and Functional Findings Associated with Fovea Plana

Klin Monbl Augenheilkd. 2022 Apr;239(4):500-512. doi: 10.1055/a-1766-7448. Epub 2022 Apr 26.

ABSTRACT

PURPOSE: To analyse structural (OCT), microvascular (OCTA), and functional changes (BCVA, mfERG) associated with fovea plana and to compare it to healthy controls.

METHODS: A retrospective observational study was performed on 13 patients (26 eyes; aged 34.46 y ± 20.26) with a clinical picture of fovea plana and 15 controls (30 eyes; aged: 41.47 y ± 14.03).

RESULTS: In fovea plana, BCVA ranged from 0.25 to 1.0, with a spherical error of – 5.5 to + 18.0 dpt. Posterior segment changes included elevated papillomacular retinal fold, uveal effusion syndrome, crowded optic discs, and hypopigmented fundus. OCTA imaging of the superficial (FAZ-S), intermediate (FAZ-I), and deep foveal avascular zone (FAZ-D) confirmed absence of foveal avascular zone (FAZ-S in 13 eyes, FAZ-I in 21 eyes, and FAZ-D in 10 eyes). Fovea plana patients had a significantly smaller FAZ-S, FAZ-I, and FAZ-D than controls (p < 0.001). Within the fovea plana group, a smaller FAZ-S correlated with reduced BCVA (p = 0.004) and with reduced mfERGs in zones 1 and 2 (p = 0.001 and p = 0.017). Also, a smaller FAZ-D showed positive correlations with the mfERG, with statistically significant values in zones 1 and 2 (p = 0.003 and p = 0.017).

CONCLUSION: In conclusion, our results confirm an altered structural, microvascular, and functional pattern in patients with a clinical picture of fovea plana. As documented by the functional microvascular interactions in our study, the developmental arrest in foveation reflects the functional maturation by means of visual acuity and central retinal function.

PMID:35472794 | DOI:10.1055/a-1766-7448

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Nevin Manimala Statistics

Two Surgical Approaches for Intraocular Lens Dislocation: Pars Plana Vitrectomy Versus Core Vitrectomy with Lens Exchange

Klin Monbl Augenheilkd. 2022 Apr;239(4):484-489. doi: 10.1055/a-1788-3967. Epub 2022 Apr 26.

ABSTRACT

PURPOSE: To compare the efficacy and safety of core vitrectomy and pars plana vitrectomy for lens exchange in patients with intraocular lens dislocation.

METHODS: This is a retrospective study conducted at one eye center in Zurich, Switzerland. We reviewed 124 eyes with dislocated intraocular lens undergoing lens exchange carried out by two surgeons between 03/2016 and 12/2019 (45 months). Intraocular pressure (IOP) and best-corrected visual acuity (BCVA) were analyzed preoperatively and at 5 time points up to 12 months after lens exchange. Data on postoperative complications were collected.

RESULTS: There were 124 eyes with intraocular lens dislocation that were referred for lens exchange. Of these eyes, 59 (48%) received core vitrectomy and 65 (52%) received pars plana vitrectomy with lens exchange. Glaucoma was more frequent in the core vitrectomy group (78%) than in the pars plana vitrectomy group (32%; p < 0.001). In the core vitrectomy group, 19 (32%) eyes presented with visual impairment, 17 (29%) eyes presented with high IOP alone, and 23 (39%) eyes presented with both at the same time prior to surgery. Mean preoperative IOP in the core vitrectomy group decreased from 22.4 ± 9.2 mmHg to 14.7 ± 3.1 mmHg 12 months after surgery (p < 0.001). Mean BCVA changed from 0.40 ± 0.41 logMAR preoperatively to 0.32 ± 0.37 logMAR at 12 months postoperatively (p = 0.598) in the core vitrectomy group. In the pars plana vitrectomy group, 44 (68%) eyes presented with a change in vision, 7 (11%) eyes presented with high IOP alone, and 14 (22%) eyes presented with pressure elevation and visual impairment at the visit prior to surgery. Mean preoperative IOP in the pars plana vitrectomy group decreased from 20.9 ± 8.3 mmHg to 15.1 ± 3.5 mmHg at 12 months after lens exchange (p < 0.001). Mean BCVA in the pars plana vitrectomy group was 0.57 ± 0.62 logMAR preoperatively and 0.22 ± 0.35 logMAR 12 months postoperatively (p < 0.001). Postoperative pressure decompensation occurred more frequently in the core vitrectomy group (20%) than in the pars plana vitrectomy group (6%; p = 0.018). There was no statistically significant difference for postoperative cystoid macular edema (p = 0.055), anisometropia (p = 0.986), and high astigmatism (p = 0.362).

CONCLUSION: Core vitrectomy and pars plana vitrectomy with lens exchange are equally efficient and safe in the management of intraocular lens dislocation.

PMID:35472791 | DOI:10.1055/a-1788-3967

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Nevin Manimala Statistics

Exposure assessment of polycyclic aromatic hydrocarbons in refined coal tar sealant applications

Int J Hyg Environ Health. 2022 Apr 23;242:113971. doi: 10.1016/j.ijheh.2022.113971. Online ahead of print.

ABSTRACT

BACKGROUND: Refined coal tar sealant (RCTS) emulsions are used to seal the surface of asphalt pavement. Nine of the 22 polycyclic aromatic hydrocarbons (PAHs) evaluated in this study are classified as known, probable, or possible human carcinogens. Exposure assessment research for RCTS workers has not been published previously.

OBJECTIVES: The overall objective of this study was to develop a representative occupational exposure assessment of PAH exposure for RCTS workers based on worksite surveys. The specific aims were to: 1) quantify full-shift airborne occupational exposures to PAHs among RCTS workers; 2) quantify workers’ dermal exposures to PAHs; 3) quantify biomarkers of PAH exposure in workers’ urine; 4) identify specific job titles associated with RCTS exposure; and 5) apply these results to a biological exposure index to assess risk of potential genotoxicity from occupational exposures.

METHODS: A total of twenty-one RCTS workers were recruited from three companies. Personal and area air samples were collected using a modification of NIOSH Method 5515. Dermal exposure was assessed by hand and neck wipes before and after shifts. Twenty-two PAHs were quantified via gas chromatography-mass spectrometry selected ion monitoring. Internal dose was estimated by quantifying select PAH metabolites in pre- and post-shift urine samples using on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry.

RESULTS: PAH levels in the worker breathing zones were highest for naphthalene, acenaphthene, and phenanthrene, with geometric means of 52.1, 11.4, and 9.8 μg/m3, respectively. Hand wipe levels of phenanthrene, fluoranthene and pyrene were the highest among the 22 PAHs with geometric means of 7.9, 7.7, and 5.5 μg/cm2, respectively. Urinary PAH biomarkers for naphthalene, fluorene, phenanthrene, and pyrene were detected in all workers and were higher for post-shift samples than those collected pre-shift. Urinary concentrations of the metabolite 1-hydroxypyrene were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) Biological Exposure Index (BEI) for this metabolite in 89 percent of post-shift samples collected on the final day of the work week or field survey. Statistically significances were found between concentrations of fluorene, naphthalene, and phenanthrene in the breathing zone of workers and their corresponding urinary PAH biomarkers. Workers were placed in two work place exposure groups: applicators and non-applicators. Applicators had higher total PAH concentrations in personal breathing zone (PBZ) air samples than non-applicators and were more likely to have post-shift hand wipe concentrations significantly higher than pre-shift concentrations. Concentrations of post-shift urinary biomarkers were higher, albeit not significantly, for applicators than non-applicators.

CONCLUSIONS: The exposure results from RCTS worker samples cannot be explained by proximal factors such as nearby restaurants or construction. Air and skin concentration levels were substantially higher for RCTS workers than previously published levels among asphalt workers for all PAHs. PAH profiles on skin wipes were more consistent with RCTS sealant product than air samples. Last day post-shift urinary concentrations of 1-hydroxypyrene greatly exceeded the ACGIH BEI benchmark of 2.5 μg/L in 25 of 26 samples, which suggests occupational exposure and risk of genotoxicity. When pyrene and benzo[a]pyrene were both detected, concentration ratios from personal exposure samples were used to calculate the adjusted BEI. Concentrations of 1-hydroxypyrene exceeded the adjusted BEIs for air, hand wipes, and neck wipes in most cases. These results indicate the need to increase safety controls and exposure mitigation for RCTS workers.

PMID:35472749 | DOI:10.1016/j.ijheh.2022.113971

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Nevin Manimala Statistics

Achilles tendon mechanical properties during walking and running are underestimated when its curvature is not accounted for

J Biomech. 2022 Apr 20;137:111095. doi: 10.1016/j.jbiomech.2022.111095. Online ahead of print.

ABSTRACT

Achilles tendon (AT) mechanical properties can be estimated using an inverse dynamic approach, taking into account the tendon internal moment arm (IMA) and its kinematic behavior. Although AT presents a curvilinear line of action, a straight-line function to estimate IMA and AT length is often utilized in the literature. In this study, we combined kinetic, kinematic and ultrasound data to understand the impact of two different approaches (straight-line vs. curvilinear) in determining AT mechanical properties in vivo (during walking and running at the self-selected speed). AT force and power were calculated based on data of AT IMA and AT length derived by both respective methods. All investigated parameters were significantly affected by the method utilized (paired t-test; p < 0.05): when using the curvilinear method IMA was about 5% lower and AT length about 1.2% higher, whereas peak and mean values of AT force and power were 5% higher when compared to the straight-line method (both in walking and running). Statistic-parametric mapping (SMP) analysis revealed significant differences in IMA during the early and the late stance phase of walking and during the late stance phase of running (p < 0.01); SPM revealed significant differences also in AT length during the entire stance phase in both locomotion modes (p < 0.01). These results confirm and extend previous findings to human locomotion: neglecting the AT curvature might be a source of error, resulting in underestimates not only of internal moment arm and tendon length, but also of tendon force and power.

PMID:35472710 | DOI:10.1016/j.jbiomech.2022.111095

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Nevin Manimala Statistics

Neutrophil Gene Expression Patterns in Multiple Trauma Patients Indicate Distinct Clinical Outcomes

J Surg Res. 2022 Apr 23;277:100-109. doi: 10.1016/j.jss.2022.03.011. Online ahead of print.

ABSTRACT

INTRODUCTION: Patients after polytrauma suffer from posttraumatic immune system dysregulation and multiple organ dysfunction. Genome-wide microarray profiling in monocytes revealed a regulatory network of inflammatory markers around the transcription factor AP-1 in severely injured patients. Recent research focuses on the role of neutrophils in posttraumatic inflammation. The aim of this study was, therefore, to evaluate the impact of this inflammatory network in neutrophils.

MATERIALS AND METHODS: Blood sampling and neutrophil separation were performed on admission of the patient and at 6 h, 12 h, 24 h, 48 h, and 72 h after trauma. Neutrophil expression levels of the target genes c-Jun, c-Fos, BCL2A, MMP-9, TIMP-1, ETS-2, IL-1β, and MIP-1β were quantified by RT-qPCR. Patients were assorted into groups according to distinct clinical parameters like massive transfusion (>10 RBC units/24 h), injury severity (ISS), 90-d survival, and the presence of traumatic brain injury (defined by ICI on head CT). Statistics were calculated by Mann-Whitney Rank-Sum Test, Receiver Operating Curves, and binary multiple logistic regression.

RESULTS: Forty severely injured patients (mean ISS 36 ± 14) were included. BCL2A, MMP-9, TIMP-1, and ETS2 levels showed a significant correlation to 90-d-survival in the early posttraumatic period (6 h-24 h). Furthermore, differential BCL2A, IL-1β, MIP-1β, and MMP-9 regulation was observed in patients requiring massive transfusion. We could further show a significant TIMP-1 response in trauma PMN associated with traumatic brain injury.

CONCLUSIONS: This study of seriously injured patients highlights very early posttraumatic transcriptional changes in PMNs, which were clearly associated with posttraumatic events and outcomes.

PMID:35472724 | DOI:10.1016/j.jss.2022.03.011

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Cortical Complexity and Connectivity during Isoflurane-induced General Anesthesia: A Rat Study

J Neural Eng. 2022 Apr 26. doi: 10.1088/1741-2552/ac6a7b. Online ahead of print.

ABSTRACT

OBJECTIVE: The investigation of neurophysiologic mechanisms of anesthetic drug-induced loss of consciousness (LOC) by using the entropy, complexity, and information integration theories at the mesoscopic level has been a hot topic in recent years. However, systematic research is still lacking.

APPROACH: We analyzed electrocorticography (ECoG) data recorded from nine rats during isoflurane-induced unconsciousness. To characterize the complexity and connectivity changes, we investigated ECoG power, symbolic dynamic-based entropy (i.e., permutation entropy (PE)), complexity (i.e., permutation Lempel-Ziv complexity (PLZC)), information integration (i.e., permutation cross mutual information (PCMI)), and PCMI-based cortical brain networks in the frontal, parietal, and occipital cortical regions.

MAIN RESULTS: Firstly, LOC was accompanied by a raised power in the ECoG beta (12-30 Hz) but a decreased power in the high gamma (55-95 Hz) frequency band in all three brain regions. Secondly, PE and PLZC showed similar change trends in the lower frequency band (0.1-45 Hz), declining after LOC (p<0.05) and increasing after recovery of consciousness (p<0.001). Thirdly, intra-frontal and inter-frontal-parietal PCMI declined after LOC, in both lower (0.1-45Hz) and higher frequency bands (55-95Hz) (p<0.001). Finally, the local network parameters of the nodal clustering coefficient and nodal efficiency in the frontal region decreased after LOC, in both the lower and higher frequency bands (p<0.05). Moreover, global network parameters of the normalized average clustering coefficient and small world index increased slightly after LOC in the lower frequency band. However, this increase was not statistically significant.

SIGNIFICANCE: The PE, PLZC, PCMI and PCMI-based brain networks are effective metrics for qualifying the effects of isoflurane.

PMID:35472693 | DOI:10.1088/1741-2552/ac6a7b

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Frequency of duodenal anatomical variants in neonatal and pediatric upper gastrointestinal tract series (UGI) and the influence of exam quality on diagnostic reporting of these

Clin Imaging. 2022 Apr 22;87:28-33. doi: 10.1016/j.clinimag.2022.04.004. Online ahead of print.

ABSTRACT

AIM: To determine frequency of duodenal anatomical variants on clinically indicated pediatric UGI examinations and determine the influence of these variants and exam quality on the reliability of diagnosis.

MATERIALS AND METHODS: Two-pediatric radiologists retrospectively reviewed 100-UGI exams performed on children ≤18-years. Exams were considered diagnostic if the duodenojejunal (DJ) flexure was identified. For diagnostic exams, readers categorized the duodenal location and shape as: normal, normal variant, or abnormal. Exam quality was assessed according to duodenal visualization, number of boluses required, and patient positioning.

RESULTS: Reader 1: 90/100 exams diagnostic -77% normal duodenum, 20% normal variant, and 3% abnormal. Reader 2: 97/100 exams diagnostic – 88% normal, 8% normal variant, and 4% abnormal. Original reports: 99/100 exams diagnostic – 92% normal, 3% normal variant, and 5% abnormal. 42% of exams were “high-quality” and 58% were “low-quality”. The number of abnormal was the same between readers in “high-quality” studies. In “low-quality” studies reader 1 and the original read diagnosed 1 further case as non-rotation which was diagnosed as a normal variant by reader 2. Two further cases were reported as non-rotation by the original reader. Inter-rater reliability was significantly higher among each pair of raters in “high quality” exams (κ 0.3; p ≤ 0.05) compared to “low quality” exams (k < 0.1 – p > 0.05).

CONCLUSION: Duodenal variants were diagnosed in 8-20% of UGI. Compromised exam quality contributes to poor interrater reliability and may result in diagnostic errors of normal variant duodenums, posing a risk for unnecessary intervention and/or delayed treatment.

PMID:35472665 | DOI:10.1016/j.clinimag.2022.04.004