A field-validated ensemble species distribution model of Eriogonum pelinophilum, an endangered subshrub in Colorado, USA.

Understanding the suitable habitat of endangered species is crucial for agencies such as the Bureau of Land Management to plan management and conservation. However, few species distribution models are directly validated, potentially limiting their application in management. In preparation for a Species Status Assessment of clay-loving wild buckwheat (Eriogonum pelinophilum), an endangered subshrub found in southwest Colorado, we ran a series of species distribution models to estimate the species' potential occupied habitat and validated these models in the field. A 1-meter resolution digital elevation model derived from LiDAR and a high-resolution geology mapping helped identify biologically relevant characteristics of the species' habitat. We employed a weighted ensemble model based on two Random Forest and one Boosted Regression Tree model, and discrimination performance of the ensemble model was high (AUC-PR = 0.793). We then conducted a systematic field survey of model habitat suitability predictions, during which we discovered 55 new subpopulations of the species and demonstrated that new species observations were strongly associated with model predictions (p < .0001, Cliff's delta = 0.575). We further refined our original models by incorporating the additional species occurrences collected in the field survey, a new explanatory variable, and a more diverse set of models. These iterative changes marginally improved performance of the ensemble model (AUC-PR = 0.825). Direct validation of species distribution models is extremely rare, and our field survey provides strong validation of our model results. This helps increase confidence to utilize predictions in planning. The final model predictions greatly improve the Bureau of Land Management's understanding of the species' habitat and increase our ability to consider potential habitat in planning land use activities such as road development and travel management.

Assessing the Safety and Efficacy of Regional Anesthesia for Lower Extremity Microvascular Reconstruction: Enhancing Recovery.

BACKGROUND: Perioperative pain, increased sympathetic tone, and peripheral vasospasm may be safely managed with regional nerve blockade during microvascular reconstruction in the lower extremity. Limited reports exist in this setting; therefore, we evaluated our use of peripheral nerve catheters (PNCs) during microvascular limb salvage to determine safety and efficacy for both patient and flap. METHODS: A single-institution, retrospective review of a prospectively maintained database on all patients with lower extremity free tissue transfers between 2012 and 2017 was completed. Patients were matched into groups based on PNC utilization. The use of intravenous narcotics including patient-controlled analgesia (PCA), oral narcotics, antiemetics, length of stay (LOS), associated pain scores, flap-related performance, and patient morbidity was recorded. RESULTS: Of 48 patients who underwent lower extremity free tissue transfer, 35 satisfied criteria for comparison. Of these, PNC was utilized in 83%. The mean pain score in the immediate postoperative period was 3.84 ± 2.47 (10-point Likert scale). PCA and narcotic use were decreased in the PNC group, and no adverse effects of the catheter were identified. Microsurgical outcomes were not adversely affected in comparison. CONCLUSION: PNC utilization for lower extremity free flap transfer significantly reduced concurrent narcotic use and attained a shorter LOS. The technique provided for safe analgesia during lower extremity free flap reconstructions satisfying the microsurgeon and the anesthesiologist.

Clinical prediction rule to determine the need for repeat ERCP after endoscopic treatment of postsurgical bile leaks.

BACKGROUND AND AIMS: In patients who have undergone ERCP with biliary stenting for postsurgical bile leaks, the optimal method (ERCP or gastroscopy) and timing of stent removal is controversial. We developed a clinical prediction rule to identify cases in which a repeat ERCP is unnecessary. METHODS: Population-based study of all patients who underwent ERCP for management of surgically induced bile leaks between 2000 and 2012. Multivariate and binary recursive partitioning analyses were performed to generate a rule predicting the absence of biliary pathology on repeat endoscopic evaluation. RESULTS: A total of 259 patients were included. On multivariate analysis, postsurgical normal alkaline phosphatase (ALP; OR, 2.26; 95% CI, 1.03-4.99), time from surgery to first ERCP < 8 days (OR, 2.47; 95% CI, 1.15-5.31), and minor leak with no other pathology on initial ERCP (OR, 6.74; 95% CI, 1.75-25.89) were independently associated with the absence of persistent bile leak and other pathology on repeat ERCP. The derived rule included laparoscopic cholecystectomy, normal postsurgical ALP, minor leak with no other pathology on initial ERCP, and an interval from initial to repeat ERCP between 4 and 8 weeks. When all 4 criteria were met, the rule had a sensitivity of 94% (95% CI, 83%-99%) and a negative predictive value of 93% (95% CI, 81%-99%). Optimism-adjusted sensitivity and negative predictive value were 88% (95% CI, 76%-96%) and 86% (95% CI, 73%-96%), respectively. CONCLUSIONS: This clinical decision rule identifies patients who can have their biliary stents removed via gastroscopy, which may improve patient safety and healthcare utilization.

Incidence of Appendicitis over Time: A Comparative Analysis of an Administrative Healthcare Database and a Pathology-Proven Appendicitis Registry.

IMPORTANCE: At the turn of the 21st century, studies evaluating the change in incidence of appendicitis over time have reported inconsistent findings. OBJECTIVES: We compared the differences in the incidence of appendicitis derived from a pathology registry versus an administrative database in order to validate coding in administrative databases and establish temporal trends in the incidence of appendicitis. DESIGN: We conducted a population-based comparative cohort study to identify all individuals with appendicitis from 2000 to2008. SETTING & PARTICIPANTS: Two population-based data sources were used to identify cases of appendicitis: 1) a pathology registry (n = 8,822); and 2) a hospital discharge abstract database (n = 10,453). INTERVENTION & MAIN OUTCOME: The administrative database was compared to the pathology registry for the following a priori analyses: 1) to calculate the positive predictive value (PPV) of administrative codes; 2) to compare the annual incidence of appendicitis; and 3) to assess differences in temporal trends. Temporal trends were assessed using a generalized linear model that assumed a Poisson distribution and reported as an annual percent change (APC) with 95% confidence intervals (CI). Analyses were stratified by perforated and non-perforated appendicitis. RESULTS: The administrative database (PPV = 83.0%) overestimated the incidence of appendicitis (100.3 per 100,000) when compared to the pathology registry (84.2 per 100,000). Codes for perforated appendicitis were not reliable (PPV = 52.4%) leading to overestimation in the incidence of perforated appendicitis in the administrative database (34.8 per 100,000) as compared to the pathology registry (19.4 per 100,000). The incidence of appendicitis significantly increased over time in both the administrative database (APC = 2.1%; 95% CI: 1.3, 2.8) and pathology registry (APC = 4.1; 95% CI: 3.1, 5.0). CONCLUSION & RELEVANCE: The administrative database overestimated the incidence of appendicitis, particularly among perforated appendicitis. Therefore, studies utilizing administrative data to analyze perforated appendicitis should be interpreted cautiously.

Validation of coding algorithms for the identification of patients hospitalized for alcoholic hepatitis using administrative data.

BACKGROUND: Epidemiologic studies of alcoholic hepatitis (AH) have been hindered by the lack of a validated International Classification of Disease (ICD) coding algorithm for use with administrative data. Our objective was to validate coding algorithms for AH using a hospitalization database. METHODS: The Hospital Discharge Abstract Database (DAD) was used to identify consecutive adults (≥18 years) hospitalized in the Calgary region with a diagnosis code for AH (ICD-10, K70.1) between 01/2008 and 08/2012. Medical records were reviewed to confirm the diagnosis of AH, defined as a history of heavy alcohol consumption, elevated AST and/or ALT (<300 U/L), serum bilirubin >34 µmol/L, and elevated INR. Subgroup analyses were performed according to the diagnosis field in which the code was recorded (primary vs. secondary) and AH severity. Algorithms that incorporated ICD-10 codes for cirrhosis and its complications were also examined. RESULTS: Of 228 potential AH cases, 122 patients had confirmed AH, corresponding to a positive predictive value (PPV) of 54% (95% CI 47-60%). PPV improved when AH was the primary versus a secondary diagnosis (67% vs. 21%; P < 0.001). Algorithms that included diagnosis codes for ascites (PPV 75%; 95% CI 63-86%), cirrhosis (PPV 60%; 47-73%), and gastrointestinal hemorrhage (PPV 62%; 51-73%) had improved performance, however, the prevalence of these diagnoses in confirmed AH cases was low (29-39%). CONCLUSIONS: In conclusion the low PPV of the diagnosis code for AH suggests that caution is necessary if this hospitalization database is used in large-scale epidemiologic studies of this condition.

Ulcerative colitis-associated hospitalization costs: a population-based study.

BACKGROUND: Hospitalization costs for ulcerative colitis (UC) following the introduction of infliximab have not been evaluated. OBJECTIVE: To study predictors of costs for UC patients who were hospitalized for a flare or colectomy. METHODS: Population-based surveillance identified adults (≥18 years of age) admitted to hospital for UC flare or colectomy between 2001 and 2009 in the Calgary Health Zone (Alberta). Medical charts were reviewed and patients stratified into three admission types: responsive to inpatient medical therapy (n=307); emergent colectomy (n=227); and elective colectomy (n=208). The annual median cost with interquartile range (IQR) was calculated. Linear regression determined the effect of admission type on hospital charges after adjusting for age, sex, smoking, comorbidities, disease extent, medication use (eg, infliximab) and year. The adjusted cost increase was presented as the percent increase with 95% CIs. Joinpoint analysis assessed for an inflection point in hospital cost after the introduction of infliximab. RESULTS: Median hospitalization cost for UC flare, emergent colectomy and elective colectomy, respectively, were: $5,499 (IQR $3,374 to $8,904), $23,698 (IQR $17,981 to $32,385) and $14,316 (IQR $11,932 to $18,331). Adjusted hospitalization costs increased approximately 6.0% annually (95% CI 4.5% to 7.5%). Adjusted costs were higher for patients who underwent an elective colectomy (percent increase cost 179.8% [95% CI 151.6% to 211.1%]) or an emergent colectomy (percent increase cost 211.1% [95% CI 183.2% to 241.6%]) than medically responsive patients. Infliximab in hospital was an independent predictor of increased costs (percent increase cost 69.5% [95% CI 49.2% to 92.5%]). No inflection points were identified. CONCLUSION: Hospitalization costs for UC increased due to colectomy and infliximab.

Risk factors for mortality in patients with alcoholic hepatitis and assessment of prognostic models: A population-based study.

BACKGROUND: Severe alcoholic hepatitis (AH) is associated with a substantial risk for short-term mortality. OBJECTIVES: To identify prognostic factors and validate well-known prognostic models in a Canadian population of patients hospitalized for AH. METHODS: In the present retrospective study, patients hospitalized for AH in Calgary, Alberta, between January 2008 and August 2012 were included. Stepwise logistic regression models identified independent risk factors for 90-day mortality, and the discrimination of prognostic models (Model for End-stage Liver Disease [MELD] and Maddrey discriminant function [DF]) were examined using areas under the ROC curves. RESULTS: A total of 122 patients with AH were hospitalized during the study period; the median age was 49 years (interquartile range [IQR] 42 to 55 years) and 60% were men. Median MELD score and Maddrey DF on admission were 21 (IQR 18 to 24) and 45 (IQR 26 to 62), respectively. Seventy-three percent of patients received corticosteroids and/or pentoxifylline, and the 90-day mortality was 17%. Independent predictors of mortality included older age, female sex, international normalized ratio, MELD score and Maddrey DF (all P<0.05). For discrimination of 90-day mortality, the areas under the ROC curves of the prognostic models (MELD 0.64; Maddrey DF 0.68) were similar (P>0.05). At optimal cut-offs of ≥22 for MELD score and ≥37 for Maddrey DF, both models excluded death with high certainty (negative predictive values 90% and 96%, respectively). CONCLUSIONS: In patients hospitalized for AH, well-known prognostic models can be used to predict 90-day mortality, particularly to identify patients with a low risk for death.

Liver stiffness by transient elastography predicts liver-related complications and mortality in patients with chronic liver disease.

BACKGROUND: Liver stiffness measurement (LSM) by transient elastography (TE, FibroScan) is a validated method for noninvasively staging liver fibrosis. Most hepatic complications occur in patients with advanced fibrosis. Our objective was to determine the ability of LSM by TE to predict hepatic complications and mortality in a large cohort of patients with chronic liver disease. METHODS: In consecutive adults who underwent LSM by TE between July 2008 and June 2011, we used Cox regression to determine the independent association between liver stiffness and death or hepatic complications (decompensation, hepatocellular carcinoma, and liver transplantation). The performance of LSM to predict complications was determined using the c-statistic. RESULTS: Among 2,052 patients (median age 51 years, 65% with hepatitis B or C), 87 patients (4.2%) died or developed a hepatic complication during a median follow-up period of 15.6 months (interquartile range, 11.0-23.5 months). Patients with complications had higher median liver stiffness than those without complications (13.5 vs. 6.0 kPa; P<0.00005). The 2-year incidence rates of death or hepatic complications were 2.6%, 9%, 19%, and 34% in patients with liver stiffness <10, 10-19.9, 20-39.9, and ≥40 kPa, respectively (P<0.00005). After adjustment for potential confounders, liver stiffness by TE was an independent predictor of complications (hazard ratio [HR] 1.05 per kPa; 95% confidence interval [CI] 1.03-1.06). The c-statistic of liver-stiffness for predicting complications was 0.80 (95% CI 0.75-0.85). A liver stiffness below 20 kPa effectively excluded complications (specificity 93%, negative predictive value 97%); however, the positive predictive value of higher results was sub-optimal (20%). CONCLUSIONS: Liver stiffness by TE accurately predicts the risk of death or hepatic complications in patients with chronic liver disease. TE may facilitate the estimation of prognosis and guide management of these patients.

The feasibility and reliability of transient elastography using Fibroscan®: a practice audit of 2335 examinations.

BACKGROUND: Liver stiffness measurement (LSM) using transient elastography is widely used in the management of patients with chronic liver disease. OBJECTIVES: To examine the feasibility and reliability of LSM, and to identify patient and operator characteristics predictive of poorly reliable results. METHODS: The present retrospective study investigated the frequency and determinants of poorly reliable LSM (interquartile range [IQR]/median LSM [IQR/M] >30% with median liver stiffness ≥7.1 kPa) using the FibroScan (Echosens, France) over a three-year period. Two experienced operators performed all LSMs. Multiple logistic regression analyses examined potential predictors of poorly reliable LSMs including age, sex, liver disease, the operator, operator experience (<500 versus ≥500 scans), FibroScan probe (M versus XL), comorbidities and liver stiffness. In a subset of patients, medical records were reviewed to identify obesity (body mass index ≥30 kg/m2). RESULTS: Between July 2008 and June 2011, 2335 patients with liver disease underwent LSM (86% using the M probe). LSM failure (no valid measurements) occurred in 1.6% (n=37) and was more common using the XL than the M probe (3.4% versus 1.3%; P=0.01). Excluding LSM failures, poorly reliable LSMs were observed in 4.9% (n=113) of patients. Independent predictors of poorly reliable LSM included older age (OR 1.03 [95% CI 1.01 to 1.05]), chronic pulmonary disease (OR 1.58 [95% CI 1.05 to 2.37), coagulopathy (OR 2.22 [95% CI 1.31 to 3.76) and higher liver stiffness (OR per kPa 1.03 [95% CI 1.02 to 1.05]), including presumed cirrhosis (stiffness ≥12.5 kPa; OR 5.24 [95% CI 3.49 to 7.89]). Sex, diabetes, the underlying liver disease and FibroScan probe were not significant. Although reliability varied according to operator (P<0.0005), operator experience was not significant. In a subanalysis including 434 patients with body mass index data, obesity influenced the rate of poorly reliable results (OR 2.93 [95% CI 0.95 to 9.05]; P=0.06). CONCLUSIONS: FibroScan failure and poorly reliable LSM are uncommon. The most important determinants of poorly reliable results are older age, obesity, higher liver stiffness and the operator, the latter emphasizing the need for adequate training.

Follow-through after calling a nurse telephone advice line: a population-based study.

BACKGROUND: Nurse telephone advice (NTA) lines, a major initiative in primary health care reform, provide symptom triage and health information. Compliance studies utilizing database analysis are frequently limited to a defined population, such as children or Emergency Department (ED) users. OBJECTIVES: To explore caller characteristics associated with following NTA advice to go to the ED, see a health care professional or self-care for Calgary, Canada (population 1 million). METHODS: NTA data were linked with utilization data to assess ED and physician visits following a call. Four nurse advice categories were defined: go to ED, health care provider in 24 hours, health care provider in 72 hours if symptoms persist and self-care. Follow-through was defined based on health care utilization within specified time periods following the call. Logistic regression identified characteristics associated with follow-through of NTA nurse advice; characteristics included age, sex, neighbourhood income, health status, time of call and type of care protocol. RESULTS: Follow-through was highest for self-care advice (83.7%), followed by ED advice (52.3%) and then 24-hour advice (43.2%). Lower follow-through on ED or 24-hour advice was associated with age <4 years, and having lower income, and the opposite was true for self-care advice. Patients with a cardiac complaint had the highest odds of following ED advice. Patients with a gastrointestinal or obstetrics/gynaecology/genitourinary complaint were less likely to follow 24-hour advice. Patients with fever were less likely to follow self-care advice. CONCLUSIONS: Understanding characteristics associated with lower follow-through may help the NTA service to refine its approaches to clients.

Prospective comparison of auto and allograft hamstring tendon constructs for ACL reconstruction.

UNLABELLED: Although allograft use for primary anterior cruciate ligament reconstruction has continued to increase during the last 10 years, concerns remain regarding the long-term function of allografts (primarily that they may stretch with time) and clinical efficacy compared with autograft tendons. We attempted to address these issues by prospectively comparing identical quadrupled hamstring autografts with allograft constructs for primary anterior cruciate ligament reconstruction in patients with a minimum followup of 3 years. Eighty-four patients (37 with autografts and 47 with allografts) were enrolled; the mean followup was 52 +/- 11 months for the autograft group and 48 +/- 8 months for the allograft group. Outcome measurements included objective and subjective International Knee Documentation Committee scores, Lysholm scores, Tegner activity scales, and KT-1000 arthrometer measurements. The two cohorts were similar in average age, acute or chronic nature of the anterior cruciate ligament rupture, and incidence of concomitant meniscal surgeries. At final followup, we found no difference in terms of Tegner, Lysholm, KT-1000, or International Knee Documentation Committee scores. Five anterior cruciate ligament reconstructions failed: three in the autograft group and two in the allograft group. Our data suggest laxity is not increased in allograft tendons compared with autografts and clinical outcome scores 3 to 6 years after surgery are similar. LEVEL OF EVIDENCE: Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Arthrodesis of the thumb metacarpophalangeal joint using a cannulated screw and threaded washer.

We describe a technique of arthrodesis of the thumb metacarpophalangeal joint that we performed in 26 patients. Indications for surgery were instability (6 patients), chronic instability with secondary degenerative joint disease (6), osteoarthritis (6), inflammatory arthritis (7), and paralytic boutonniere (1). The technique uses the cup-and-cone method of decortication and positioning with the internal fixation using a 3.0-mm partially threaded cannulated screw and threaded washer (Synthes, Paoli, PA). Twenty-five of 26 joints had clinical and radiographic fusion. Average time to radiographic fusion for 24 patients (1 nonunion, 1 patient without x-rays until 4 months) was 10 weeks. Long-term follow-up evaluation was available for 20 patients and averaged 32 months (range, 21-44 months). All 20 had stable radiographic fusion with maintenance of the fusion angle. There were no infections and no need for hardware removal. Our results indicate that this technique for arthrodesis of the thumb metacarpophalangeal joint is effective and reliable, is accomplished easily, and has a low incidence of complications.