Biostat (United States)

Roundabout capacity is primarily estimated by gap-acceptance or by geometric models. The 2010 Highway Capacity Manual (HCM 10) uses a gap-acceptance model developed by Siegloch with empirically derived values of critical gap and headway for single-lane and two-lane entries. A geometric capacity model was developed by Kimber and Hollis that diverged from gap-based models. The capacity of up to four lane entries was empirically derived from six geometric parameters. In 2012 capacity data were collected as part of the FHWA project, Assessment of Roundabout Capacity Models for the Highway Capacity Manual. These data were used to produce HCM6, an update of the HCM 2010. In HCM6, a capacity curve was fitted through all the capacity data for single-lane roundabouts. The large scatter of data about the mean capacity line suggests that the single-lane roundabouts may be separated into different geometric types to improve accuracy. To investigate this hypothesis, the capacity data were separated into two geometrically distinct types of single-lane roundabouts: smaller, compact and larger, curvilinear. The range of data for the disaggregated and aggregated data was compared. Also, a capacity line was derived for each type using the geometric capacity model and compared with the disaggregated data with the HCM6 method. The results demonstrate that differences in geometry, absent in HCM6, explain the wide data range. This was further confirmed by the geometric model that gave a good fit to both sets of data. These results indicate that the accuracy of capacity prediction is improved by including geometric variation.

OBJECTIVEThe effect of therapeutic strategies on cardiovascular (CV) disease can be evaluated by monitoring changes in CV risk biomarkers. This study investigated the effect of a structured self-monitoring of blood glucose (SMBG) protocol and the resulting improvements in glycemic control on changes in high-sensitivity C-reactive protein (hs-CRP) in insulin-naïve patients with type 2 diabetes.RESEARCH DESIGN AND METHODSThe Structured Testing Program (STeP) study was a prospective, cluster-randomized, multicenter trial in which 483 poorly controlled, insulin-naïve patients with type 2 diabetes were randomized to active control (ACG) or structured testing (STG) that included quarterly structured SMBG. Changes in A1C, hs-CRP, and glycemic variability (STG subjects only) were measured at baseline and quarterly.RESULTSReductions in geometric mean hs-CRP values were significantly greater in the STG group at months 3 (P = 0.005), 6 (P = 0.0003), and 12 (P = 0.04) than in the ACG group. STG patients at high CV risk (>3 mg/L) showed significantly greater reductions in hs-CRP levels than ACG patients at high CV risk: −3.64 mg/dL (95% CI −4.21 to −3.06) versus −2.18 mg/dL (−2.93 to −1.43), respectively (P = 0.002). There was a strong correlation between reductions in hs-CRP and A1C in both groups: standardized coefficient (β) was 0.25 for the entire cohort (P < 0.0001), 0.31 for STG (P < 0.0001), and 0.16 for ACG (P = 0.02).CONCLUSIONSReductions in hs-CRP level are associated with reductions in A1C but not reductions in lipids or glycemic variability. Comprehensive structured SMBG-based interventions that lower A1C may translate into improvements in CV risk, as evidenced by levels of the biomarker hs-CRP.

149 Background: Accelerated partial breast irradiation (APBI) is commonly used in early-stage breast cancer. The SAVI Collaborative Research Group is a multi-institutional group created to study outcomes in patients who received APBI utilizing strut-based brachytherapy. This analysis reports the acute and late toxicities for patients with greater than 2-year follow-up (F/U) from this study. Methods: 904 APBI patients (ductal carcinoma in situ [n=267] or invasive breast cancer [n=637]), received HDR brachytherapy (34 Gy in 10 fractions) using the SAVI device (Cianna Medical). Patients with dosimetry and documented follow-up were evaluated within 6 weeks of treatment for early adverse events (AEs), and at 1 year, 2 years, and beyond for late AEs. Dosimetric parameters were evaluated with respect to toxicity and will be presented. Results: In 212 patients (median age 62.9 years, range 40-88) all with follow-up greater than 24 months, the median tumor size was 12mm. As of last follow-up (&gt;24 months) cumulative rates of erythema and hyperpigmentation of grade 2 or higher were 1.4% and 0.5%. The incidence of grade 2 or higher telangiectasia, seroma and fat necrosis were 2.8%, 2.8%, and 0.5% respectively. Conclusions: Adverse events for APBI with SAVI are low in incidence, low in grade and compare favorably to other HDR APBI methods.

We thank Stephens et al. (1) for their comments in response to the Structured Testing Program (STeP) study. It is evident that we share an interest in ensuring that health care resources are used effectively, and we therefore welcome the opportunity to address the issues you have raised. As noted in the letter, a number of studies in noninsulin-treated diabetes have shown data similar to those of Stephens et al.—suggesting that self-monitoring of blood glucose (SMBG), as it is typically done, offers little or no glycemic benefit (2,3). We do …

BackgroundNeurologic Post Treatment Lyme disease (nPTLS) and Chronic Fatigue (CFS) are syndromes of unknown etiology. They share features of fatigue and cognitive dysfunction, making it difficult to differentiate them. Unresolved is whether nPTLS is a subset of CFS.Methods and Principal FindingsPooled cerebrospinal fluid (CSF) samples from nPTLS patients, CFS patients, and healthy volunteers were comprehensively analyzed using high-resolution mass spectrometry (MS), coupled with immunoaffinity depletion methods to reduce protein-masking by abundant proteins. Individual patient and healthy control CSF samples were analyzed directly employing a MS-based label-free quantitative proteomics approach. We found that both groups, and individuals within the groups, could be distinguished from each other and normals based on their specific CSF proteins (p<0.01). CFS (n = 43) had 2,783 non-redundant proteins, nPTLS (n = 25) contained 2,768 proteins, and healthy normals had 2,630 proteins. Preliminary pathway analysis demonstrated that the data could be useful for hypothesis generation on the pathogenetic mechanisms underlying these two related syndromes.ConclusionsnPTLS and CFS have distinguishing CSF protein complements. Each condition has a number of CSF proteins that can be useful in providing candidates for future validation studies and insights on the respective mechanisms of pathogenesis. Distinguishing nPTLS and CFS permits more focused study of each condition, and can lead to novel diagnostics and therapeutic interventions.

OBJECTIVETo assess the effectiveness of structured blood glucose testing in poorly controlled, noninsulin-treated type 2 diabetes.RESEARCH DESIGN AND METHODSThis 12-month, prospective, cluster-randomized, multicenter study recruited 483 poorly controlled (A1C ≥7.5%), insulin-naïve type 2 diabetic subjects from 34 primary care practices in the U.S. Practices were randomized to an active control group (ACG) with enhanced usual care or a structured testing group (STG) with enhanced usual care and at least quarterly use of structured self-monitoring of blood glucose (SMBG). STG patients and physicians were trained to use a paper tool to collect/interpret 7-point glucose profiles over 3 consecutive days. The primary end point was A1C level measured at 12 months.RESULTSThe 12-month intent-to-treat analysis (ACG, n = 227; STG, n = 256) showed significantly greater reductions in mean (SE) A1C in the STG compared with the ACG: −1.2% (0.09) vs. −0.9% (0.10); Δ = −0.3%; P = 0.04. Per protocol analysis (ACG, n = 161; STG, n = 130) showed even greater mean (SE) A1C reductions in the STG compared with the ACG: −1.3% (0.11) vs. −0.8% (0.11); Δ = −0.5%; P < 0.003. Significantly more STG patients received a treatment change recommendation at the month 1 visit compared with ACG patients, regardless of the patient’s initial baseline A1C level: 179 (75.5%) vs. 61 (28.0%); <0.0001. Both STG and ACG patients displayed significant (P < 0.0001) improvements in general well-being (GWB).CONCLUSIONSAppropriate use of structured SMBG significantly improves glycemic control and facilitates more timely/aggressive treatment changes in noninsulin-treated type 2 diabetes without decreasing GWB.

To determine the types of microorganisms and their frequency of isolation on the external ocular surface in children wearing soft contact lenses on a daily wear schedule. Children aged 8 to 14 years were fitted with commercially available, soft contact lenses which were worn on a daily wear basis. The upper bulbar conjunctiva and the lower lid margins of each eye were swabbed at baseline and then at 6-monthly intervals for 2 years during lens wear. Swabs were processed, cultured and microorganisms identified using standard microbiological techniques. At baseline, 36% of the upper bulbar conjunctivae and 53% of the lower lid margins were contaminated with predominantly gram-positive bacteria. Recovery of samples with positive growth from the upper bulbar conjunctivae decreased during lens wear and ranged from 27 to 14%. The difference was statistically significant at the 12-month visit(14%, p = 0.011). The lower lid margins generally showed similar levels of contamination as at baseline except for less contamination at the 12-month visit (33%) (p = 0.05). Staphylococcus epidermidis and Propionibacterium sp. were the predominant microorganisms isolated from both the sites with and without lens wear. Gram-negative bacteria were infrequent and when isolated, the numbers of colonies were few. Fungus was isolated in a small percent (ranging from 0 to 4.8%) of eyes at various time points. The external ocular surface of children is contaminated with gram-positive bacteria that are resident microbiota. During lens wear, there was a trend for lesser recovery of organisms from the upper bulbar conjunctival samples,but there was no change in the type of microorganisms isolated. At all times, lower lid margins showed consistently greater colonization and is a source of potential contamination of the conjunctival surface.