Browsing by Author "Slaven, James"

Now showing 1 - 10 of 13
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    Confidence Intervals for Asbestos Fiber Counts: Approximate Negative Binomial Distribution
    (Oxford University Press, 2017-03-01) Bartley, David; Slaven, James; Harper, Martin; Biostatistics, School of Public Health
    The negative binomial distribution is adopted for analyzing asbestos fiber counts so as to account for both the sampling errors in capturing only a finite number of fibers and the inevitable human variation in identifying and counting sampled fibers. A simple approximation to this distribution is developed for the derivation of quantiles and approximate confidence limits. The success of the approximation depends critically on the use of Stirling’s expansion to sufficient order, on exact normalization of the approximating distribution, on reasonable perturbation of quantities from the normal distribution, and on accurately approximating sums by inverse-trapezoidal integration. Accuracy of the approximation developed is checked through simulation and also by comparison to traditional approximate confidence intervals in the specific case that the negative binomial distribution approaches the Poisson distribution. The resulting statistics are shown to relate directly to early research into the accuracy of asbestos sampling and analysis. Uncertainty in estimating mean asbestos fiber concentrations given only a single count is derived. Decision limits (limits of detection) and detection limits are considered for controlling false-positive and false-negative detection assertions and are compared to traditional limits computed assuming normal distributions.
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    Effect of CPAP on airway reactivity and airway inflammation in children with moderate-severe asthma
    (Wiley, 2019-04) Praca, Eduardo; Jalou, Hasnaa; Krupp, Nadia; Delecaris, Angela; Hatch, Joseph; Slaven, James; Gunst, Susan J.; Tepper, Robert S.; Biostatistics, School of Public Health
    BACKGROUND AND OBJECTIVE: Asthma is characterized by airway hyperreactivity and airway inflammation. We previously demonstrated that adults with mild well-controlled asthma exhibited a marked decrease in airway reactivity (PC20 increased >2-fold) after using nocturnal continuous positive airway pressure (CPAP) for 1 week. If CPAP produces a similar suppression of airway reactivity in children with moderate-severe asthma, who require chronic use of corticosteroids, then this non-pharmacological therapy might provide a beneficial alternative or supplemental therapy in these subjects. METHODS: Children aged 8-17 years with moderate-severe asthma were treated with 4 weeks of nocturnal CPAP (8-10 cm H2 O) or sham CPAP (<2 cm H2 O). Adherence was monitored with a modem installed in the equipment or by memory cards. Airway reactivity, assessed by methacholine bronchial challenge, was measured prior to and following treatment. RESULTS: The percentage of subjects adherent to treatment was similar in both groups (19/27 CPAP vs 19/28 sham, ~70%). There was a tendency for PC20 to increase with treatment in both groups (3.0-5.3 mg/mL CPAP vs 3.2 to 4.3 mg/mL sham, P = 0.083); however, the change did not differ significantly between groups (P = 0.569). CONCLUSION: We found that the 4-week treatment with nocturnal CPAP did not produce a twofold suppression of airway reactivity in children with moderate-severe asthma.
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    EUS pancreatic function testing and dynamic pancreatic duct evaluation for the diagnosis of exocrine pancreatic insufficiency and chronic pancreatitis
    (Elsevier, 2020) DeWitt, John M.; Al-Haddad, Mohammad A.; Easler, Jeffrey J.; Sherman, Stuart; Slaven, James; Gardner, Timothy B.; Medicine, School of Medicine
    Background and Aims EUS and endoscopic pancreatic function tests (ePFTs) may be used to diagnose minimal- change chronic pancreatitis (MCCP). The impact of evaluation for exocrine pancreatic insufficiency (EPI) and real-time assessment of EUS changes after intravenous secretin on the clinical diagnosis of MCCP is unknown. Methods Patients with suspected MCCP underwent baseline EUS assessment of the pancreatic parenchyma and measurement of the main pancreatic duct (B-MPD) in the head, body, and tail. Human secretin 0.2 μg/kg IV was given followed 4, 8, and 12 minutes later by repeat MPD (S-MPD) measurements. Duodenal samples at 15, 30, and 45 minutes were aspirated for bicarbonate concentration. Endoscopists rated the percent clinical likelihood of CP: (1) before secretin; (2) after secretin but before aspiration; and (3) after bicarbonate results. Results 145 consecutive patients (mean age 44±13 years; 98F) were diagnosed with EPI (n=32; 22%). S-MPD/B-MPD ratios in the tail 4 and 8 minutes after secretin were higher in the group with normal exocrine function. Ratios at other times, locations and duodenal fluid volumes were similar between the 2 groups. A statistically significant change in the median percent likelihood of CP was noted after secretin in all groups. The sensitivity and specificity of EPI for the EUS diagnosis of CP (≥5 criteria) were 23.4% (95% CI, 12.3-38.0) and 78.6% (95% CI, 69.1-86.2), respectively. Conclusion Real-time EUS findings and ePFTs have a significant impact on the clinical assessment of MCCP. The diagnosis of EPI shows poor correlation with the EUS diagnosis of MCCP.
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    Failure Mode Analysis of the Endologix Endograft
    (Elsevier, 2016-09) Lemmon, Gary W.; Motaganahalli, Rahgu L.; Chang, Tiffany; Slaven, James; Aumiller, Ben; Kim, Bradford J.; Dalsing, Michael C.; Department of Surgery, IU School of Medicine
    Objective Type III (T-III) endoleaks following endovascular aneurysm repair (EVAR) remain a major concern. Our center experienced a recent concentration of T-III endoleaks requiring elective and emergency treatment and prompted our review of all EVAR implants over a 40-month period from April 2011 until August 2014. This report represents a single center experience with T-III endoleak management with analysis of factors leading to the T-III-related failure of EVAR. Methods A retrospective review of all the operative reports, medical records, and computed tomography scans were reviewed from practice surveillance. Using Society for Vascular Surgery aneurysm reporting standards, we analyzed the morphology of the aneurysms before and after EVAR implant using computed tomography. Index procedure and frequency of reinterventions required to maintain aneurysm freedom from rupture were compared across all devices using SAS v 9.4 (SAS Institute, Inc, Cary, NC). Major adverse events (MAEs) requiring secondary interventions for aneurysm treatment beyond primary implant were analyzed for methods of failure. Aneurysm morphology of patients requiring EVAR was compared across all endograft devices used for repair. For purposes of MAE analysis, patients receiving Endologix (ELX) endograft were combined into group 1; Gore, Cook, and Medtronic endograft patients were placed into group 2. Results Overall, technical success and discharge survival were achieved in 97.3% and 98% of patients regardless of device usage. There was no significant device related difference identified between patient survival or freedom from intervention. MAEs involving aneurysm treatment were over seven-fold more frequent with ELX (group 1) vs non-ELX (group 2) endografts (P < .01). Group 1 patients with aneurysm diameters larger than 65 mm were associated with a highly significant value for development of a T-III endoleak (odds ratio, 11.16; 95% confidence interval, 2.17, 57.27; P = .0038). Conclusions While EVAR technical success and survival were similar across all devices, ELX devices exhibited an unusually high incidence of T-III endoleaks when implanted in abdominal aortic aneurysms with a diameter of more than 65 mm. Frequent reinterventions were required for Endologix devices for prevention of aneurysm rupture due to T-III endoleaks.
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    Glutathione-S-transferase P1 may predispose children to a decline in pulmonary function after stem cell transplant
    (Wiley, 2017-07) Stark, Julie; Renbarger, Jamie; Slaven, James; Yu, Zhangsheng; Then, Jenny; Skiles, Jodi; Davis, Stephanie; Pediatrics, School of Medicine
    RATIONALE: Pulmonary complications after hematopoietic stem cell transplant (SCT) are associated with increased mortality. Genetic markers for those at risk for pulmonary impairment post-SCT have not been widely investigated. METHODS: Forty-nine patients were retrospectively selected from a single institution's biorepository with linked clinical data. All subjects performed pre-SCT PFTs. Genotyping was conducted using the Infinium Exome-24 BeadChip. Four single nucleotide polymorphisms (SNPs) were selected (rs1800871, rs1695, rs1800629, rs12477314) and evaluated for association with PFT parameters as change over time from baseline. Associations between SNPs and PFT parameters were assessed and adjusted for the following confounding variables: age, gender, and race. RESULTS: Using the recessive genetic model, patients with one or two minor alleles for the glutathione S-transferase P1 (GSTP1) SNP rs1695 had a lower decline in FEV1 and FEF25-75 at 1-year post-SCT compared to patients who were homozygous for the ancestral allele (adjusted P-values <0.01 and 0.02, respectively). No other SNPs were significantly associated with other PFT parameters. CONCLUSIONS: Our findings suggest that GSTP1 genotype may be associated with lung function during the first year post-SCT. Identifying and investigating genes that predispose patients to pulmonary complications after SCT may allow for more personalized patient management based on pre-emptive genetic testing. The glutathione S-transferase gene merits further investigation.
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    Impact of the COVID-19 Pandemic on Cystic Fibrosis Pulmonary Exacerbations
    (Indiana University, 2020) Patel, Shreya; Thompson, Misty; Slaven, James; Ren, Clement L.; Pediatrics, School of Medicine
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    Impact of the COVID-19 Pandemic on Pediatric Cystic Fibrosis Pulmonary Exacerbations
    (2020) Patel, Shreya; Thompson, Misty; Slaven, James; Sanders, Don; Ren, Clement; Pediatrics, School of Medicine
    To assess the impact of COVID-19 restrictions on cystic fibrosis (CF) pulmonary exacerbations (PEx) we performed a retrospective review of PEx events at our CF Center and compared the rate of PEx in 2019 vs 2020. Restrictions on social interaction due to the COVID-19 pandemic were associated with a lower rate of PEx at our pediatric CF Center, suggesting that these restrictions also reduced exposure to other respiratory viral infection in children with CF.
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    A pilot study of ADRA2A genotype association with doses of dexmedetomidine for sedation in pediatric patients.
    (Wiley, 2022-06) Gallaway, Katherine A.; Skaar, Todd C.; Biju, Ashwin; Slaven, James; Tillman, Emma M.
    STUDY OBJECTIVE: Dexmedetomidine is titrated to achieve sedation in the pediatric and cardiovascular intensive care units (PICU and CVICU). In adults, dexmedetomidine response has been associated with an ADRA2A polymorphism (rs1800544); CC genotype is associated with an increased sedative response compared with GC and GG. To date, this has not been studied in children. DESIGN: We conducted a pilot study to determine whether ADRA2A genotype is associated with dexmedetomidine dose in children. MEASUREMENTS AND MAIN RESULTS: Forty intubated PICU or CVICU patients who received dexmedetomidine as a continuous infusion for at least 2 days were genotyped for ADRA2A with a custom-designed TaqMan® Assay. Ten (25%) subjects were wildtype (GG), 15 (37.5%) were heterozygous (GC), and 15 (37.5%) were homozygous (CC) variant. The maximum dexmedetomidine doses (mCg/kg/h) were not different between genotype groups CC (1, 0.3-1.2), GC (1, 0.3-1.3), and GG (0.8, 0.3-1.2), (p = 0.37); neither were mean dexmedetomidine doses for these respective genotype groups 0.68 (0.24-1.07), 0.72 (0.22-0.98), 0.58 (0.3-0.94), (p = 0.67). CONCLUSIONS: These findings did not confirm the results from adult studies where ADRA2A polymorphisms correlate with dexmedetomidine response, therefore highlighting the need for pediatric studies to validate PGx findings in adults prior to implementation in pediatrics.
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    Research to Encourage Exercise for Fibromyalgia (REEF): Use of Motivational Interviewing, Outcomes From a Randomized-controlled Trial
    (The Clinical Journal of Pain, 2013) Ang, Dennis C.; Kaleth, Anthony S.; Bigatti, Silvia; Mazzuca, Steven A.; Jensen, Mark P.; Hilligoss, Janna; Slaven, James; Saha, Chandan
    Objectives Regular exercise is associated with important benefits in patients with fibromyalgia (FM). Unfortunately, long-term maintenance of exercise after a structured program is rare. The present study tested the efficacy of Motivational Interviewing (MI) to promote exercise and improve symptoms in patients with FM. Methods 216 patients with FM were randomized to 6 MI sessions (n=107) or an equal number of FM self-management lessons (education control/EC, n=109). Co-primary endpoints were an increase of 30 minutes in moderate-vigorous physical activity and improvement in the Fibromyalgia Impact Questionnaire-Physical Impairment (FIQ-PI) score, assessed at pre-treatment, post-treatment, and 3- and 6-month follow-up. Secondary outcomes included clinically meaningful improvements in FIQ score, pain severity ratings, and a 6-minute walk test. Results There were no significant treatment group differences in either co-primary endpoint at 6-month follow-up. However, more MI participants than controls exhibited meaningful improvements in FIQ score at 6-month follow-up (62.9% vs. 49.5%, p=0.06). Compared to EC subjects, MI subjects also displayed a larger increment in their 6-minute walk test (43.9 vs. 24.8 meters, p=0.03). Additionally, MI was superior to EC in increasing the number of hours of physical activity immediately post-intervention and in reducing pain severity both immediately after the intervention and at 3-month follow-up. Conclusions Despite a lack of benefits on long term outcome, MI appears to have short-term benefits with respect to self-report physical activity and clinical outcomes. This is the first study in FM that explicitly addresses exercise maintenance as a primary aim.
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    A Survey of Internal Medicine Residents: Their Learning Environments, Bias and Discrimination Experiences, and Their Support Structures
    (Dovepress, 2021-06-23) Sotto-Santiago, Sylk; Mac, Jacqueline; Slaven, James; Maldonado, Maria; Medicine, School of Medicine
    Purpose: While there is an emerging body of literature that demonstrates how racism and bias negatively impact the experiences of physicians and trainees from underrepresented groups in medicine in the US, little is known about the experiences of internal medicine trainees and their learning environments. The purpose of this study was to examine these learning environments and explore trainees' perceptions of race/ethnicity-related topics. Methods: A 35-item confidential electronic survey was disseminated to trainees from 11 internal medicine training programs in the US. A total of 142 trainees participated. Purposive sampling ensured alignment with 2018 IM trainee demographics by sex, race and ethnicity. Analyses were performed including chi-square, Fisher's exact tests, and logistic regression. Results: Key findings reveal 63% of respondents perceived disparities in the care provided to diverse patients. Two in three respondents were confident that their institution would respond to discrimination, but only 1/3 of respondents perceived appropriate reporting mechanisms. Black/African American trainees reported needing to minimize aspects of their race and were less likely to perceive their institutions as being supportive to people of color. Conclusion: Access to timely information about trainees' experiences with discrimination and bias in graduate medical education is imperative to disrupt systemic racism and health inequities. Findings suggest a perceived difference in health care provided to minoritized groups, a gap in formal mechanisms for reporting racism and discrimination experienced by trainees, and environments that challenge a sense of belonging. Findings add to current literature exposing the experience of underrepresented trainees in the US.