True Incidence Rate Research Articles

Geospatial Visualization of Mobile Stroke Unit Dispatches: A Method to Optimize Service Performance

Background: Timely treatment of acute ischemic stroke is crucial to optimize outcomes. Mobile stroke units (MSU) have demonstrated ultrafast treatment compared to standard emergency care. Geospatial analysis of the distribution of MSU cases to optimize service delivery has not been reported. Methods: We aggregated all first-year MSU dispatch occurrences and all cases classified by clinical teams as true stroke by zip code and calculated dispatch and true stroke incidence rates. We mapped dispatch and stroke cases and symbolized incidence rates by standard deviation. We confirmed visual impressions of clusters from map inspection by local Moran’s I, boxplot inspection, and t test. We calculated service areas using drive times to meet dispatch and true stroke need. Results: A significant cluster of high dispatch incident rate was confirmed around our MSU base in urban Memphis within a 5-min driving area supporting the initial placement of the MSU based on 911 activation. A significant cluster of high true stroke rate was confirmed to the east of our MSU base in suburban Memphis within a 10-min driving area. Mean incident longitude of cases of true stroke versus disregarded status was significantly eastward (p = 0.001785). Conclusion: Our findings will facilitate determination of socio-spatial antecedents of neighborhood overutilization of 911 and MSU services in our urban neighborhoods and service delivery optimization to reach neighborhoods with true stroke burden.

Noncatastrophic and catastrophic fractures in racing Thoroughbreds at the Hong Kong Jockey Club.

Reports of fractures in racehorses have predominantly focused on catastrophic injuries, and there are limited data identifying the location and incidence of fractures that did not result in a fatal outcome. To describe the nature and the incidence of noncatastrophic and catastrophic fractures in Thoroughbreds racing at the Hong Kong Jockey Club (HKJC) over seven racing seasons. Retrospective cohort study. Data of fractures sustained in horses while racing and of race characteristics were extracted from the HKJC Veterinary Management Information System (VMIS) and Racing Information System (RIS), respectively. The fracture event was determined from the first clinical entry for each specific injury. The incidence rates of noncatastrophic and catastrophic fractures were calculated per 1000 racing starts for racetrack, age, racing season, sex and trainer. One hundred and seventy-nine first fracture events occurred in 64,807 racing starts. The incidence rate of noncatastrophic fractures was 2.2 per 1000 racing starts and of catastrophic fractures was 0.6 per 1000 racing starts. Fractures of the proximal sesamoid bones represented 55% of all catastrophic fractures, while the most common noncatastrophic fractures involved the carpus and the first phalanx. Significant associations were detected between the incidence of noncatastrophic fractures and sex, trainer and racing season. The first fracture event was used to calculate the incidence rate in this study and may have resulted in underestimation of the true incidence rate of fractures in this population. However, given the low number of recorded fracture events compared with the size of the study population, this underestimation is likely to be small. There were 3.6 times as many noncatastrophic fractures as catastrophic fractures in Thoroughbreds racing in Hong Kong between 2004 and 2011. Noncatastrophic fractures interfere with race training schedules and may predispose to catastrophic fracture. Future analytical studies on noncatastrophic racing fractures should be a priority for the racing industry.

On Estimation of the Hazard Function From Population-Based Case–Control Studies

ABSTRACTThe population-based case–control study design has been widely used for studying the etiology of chronic diseases. It is well established that the Cox proportional hazards model can be adapted to the case–control study and hazard ratios can be estimated by (conditional) logistic regression model with time as either a matched set or a covariate. However, the baseline hazard function, a critical component in absolute risk assessment, is unidentifiable, because the ratio of cases and controls is controlled by the investigators and does not reflect the true disease incidence rate in the population. In this article, we propose a simple and innovative approach, which makes use of routinely collected family history information, to estimate the baseline hazard function for any logistic regression model that is fit to the risk factor data collected on cases and controls. We establish that the proposed baseline hazard function estimator is consistent and asymptotically normal and show via simulation that it performs well in finite samples. We illustrate the proposed method by a population-based case–control study of prostate cancer where the association of various risk factors is assessed and the family history information is used to estimate the baseline hazard function. Supplementary materials for this article are available online.

Visual Impairment Registry of Patients from North Kolkata, Eastern India: A Hospital-based Study.

Purpose:To study the demographic profile, severity and causes of visual impairment among registered patients in a tertiary care hospital in north Kolkata, eastern India, and to assess the magnitude of under-registration in that population.Methods:This is a retrospective analytical study. A review of all visually impaired patients registered at our tertiary care hospital during a ten-year period from January 2005 to December 2014, which is entitled for certification of people of north Kolkata, eastern India (with a population denominator of 1.1 million), was performed. Overall, 2472 eyes of 1236 patients were analyzed in terms of demographic characteristics, cause of visual impairment, and percentage of visual disability as per the guidelines established by the government of India.Results:Male patients (844, 68.28%; 95% confidence interval [CI], 65.69-70.87) registered more often than female patients (392; 31.72%, P = 0.0004). The registration rate for visual impairment was 11.24 per 100,000 per annum; this is not the true incidence rate, as both new patients and those visiting for renewal of certification were included in the study. Optic atrophy was the most common cause of visual impairment (384 eyes, 15.53%; 95% CI, 14.1-16.96).Conclusion:Commonest cause of visual impairment was optic atrophy followed by microphthalmos. Under-registration is a prevalent problem as the registration system is voluntary rather than mandatory, and female patients are more likely to be unregistered in this area.

Incidence and Risk Factors of Cholangitis after Hepaticojejunostomy

BackgroundAfter hepatobiliary-pancreatic surgery, hepaticojejunostomy cholangitis is a rare condition; the true incidence rate of postoperative cholangitis is unknown. Therefore, our study aimed to determine the incidence rate and timing of postoperative cholangitis after biliary-enteric anastomosis, and to evaluate risk factors and management strategies. MethodsOur single-center retrospective study included 583 patients who had undergone biliary-enteric anastomosis for hepatobiliary-pancreatic diseases. Demographic and treatment data were extracted from the medical records, and the association between potential risk factors and the development of postoperative cholangitis evaluated using a prospectively collected database. ResultsPostoperative cholangitis developed in 45/583 patients (incidence rate, 7.7%), on average 18.3±27.4 months (median = 6.9 months) after surgery. On multivariate analysis, the following factors were independently associated with postoperative cholangitis after biliary-enteric anastomosis: male sex, benign condition, and postoperative complication with a Clavien-Dindo classification grade > III. Among patients with postoperative cholangitis, a biliary stricture developed in 57.8% (26/45) of cases. Percutaneous balloon dilatation (73.1%) and endoscopic stenting (11.5%) were used as initial treatment of the stricture, with surgical revision being required in only 15.4% of cases of hepaticojejunostomy stricture. ConclusionBiliary-enteric anastomotic cholangitis after hepaticojejunostomy is a distinct disease process. Although non-operative management of postoperative cholangitis is successful in many cases, further research is required to better understand patient- and physician-related factors that predispose patients to postoperative cholangitis.

Osteoporotic hip fractures in Black South Africans: a regional study.

Developing countries are predicted to bear the burden of osteoporosis in the coming decades. This study was undertaken to review earlier reports that osteoporotic hip fractures are rare in Black Africans. In an observational study, the incidence rates and relative risk ratios (RRR) of osteoporotic hip fractures were calculated in the Black population, aged 60years and older, residing in the eThekwini region of South Africa. All Black subjects, presenting with a minimal trauma hip fracture to five public hospitals in the region, entered the study. Descriptive statistics were applied to show differences in age and sex. Eighty-seven subjects were enrolled in the study with a mean age of 76.5 ± 10.5years and the sex ratio of women to men was 2.5:1. Although men were younger than women, this was not significant (74.2 ± 12.3 vs. 77.4 ± 9.6years, p = 0.189). The age-adjusted rate was 69.2 per 100,000p.a. for women and 73.1 per 100,000p.a. for men. There was a significant increase in the relative risk ratios for hip fractures after the age of 75years in the total cohort and in women and men. Except for the 65-69-year age group, there was no significant difference in the age-adjusted RRR between women and men. This study represents the largest number of hip fractures recorded in Black Africans. Although the incidence rate is approximately tenfold higher than previously recorded, it remains amongst the lowest globally. A national registry inclusive of private and public sector is required to establish the true incidence rate of hip fractures in Black Africans.

Incidence rate estimation, periodic testing and the limitations of the mid-point imputation approach.

BackgroundIt is common to use the mid-point between the latest-negative and earliest-positive test dates as the date of the infection event. However, the accuracy of the mid-point method has yet to be systematically quantified for incidence studies once participants start to miss their scheduled test dates.MethodsWe used a simulation-based approach to generate an infectious disease epidemic for an incidence cohort with a high (80–100%), moderate (60–79.9%), low (40–59.9%) and poor (30–39.9%) testing rate. Next, we imputed a mid-point and random-point value between the participant’s latest-negative and earliest-positive test dates. We then compared the incidence rate derived from these imputed values with the true incidence rate generated from the simulation model.ResultsThe mid-point incidence rate estimates erroneously declined towards the end of the observation period once the testing rate dropped below 80%. This decline was in error of approximately 9%, 27% and 41% for a moderate, low and poor testing rate, respectively. The random-point method did not introduce any systematic bias in the incidence rate estimate, even for testing rates as low as 30%.ConclusionsThe mid-point assumption of the infection date is unjustified and should not be used to calculate the incidence rate once participants start to miss the scheduled test dates. Under these conditions, we show an artefactual decline in the incidence rate towards the end of the observation period. Alternatively, the single random-point method is straightforward to implement and produces estimates very close to the true incidence rate.

Identification of diagnostic peptide regions that distinguish Zika virus from related mosquito-borne Flaviviruses.

Zika virus (ZIKV) is a member of the Flavivirus genus of positive-sense single-stranded RNA viruses, which includes Dengue, West Nile, Yellow Fever, and other mosquito-borne arboviruses. Infection by ZIKV can be difficult to distinguish from infection by other mosquito-borne Flaviviruses due to high sequence similarity, serum antibody cross-reactivity, and virus co-circulation in endemic areas. Indeed, existing serological methods are not able to consistently differentiate ZIKV from other Flaviviruses, which makes it extremely difficult to accurately calculate the incidence rate of Zika-associated Guillain-Barre in adults, microcephaly in newborns, or asymptomatic infections within a geographical area. In order to identify Zika-specific peptide regions that could be used as serology reagents, we have applied comparative genomics and protein structure analyses to identify amino acid residues that distinguish each of 10 Flavivirus species and subtypes from each other by calculating the specificity, sensitivity, and surface exposure of each residue in relevant target proteins. For ZIKV we identified 104 and 116 15-mer peptides in the E glycoprotein and NS1 non-structural protein, respectively, that contain multiple diagnostic sites and are located in surface-exposed regions in the tertiary protein structure. These sensitive, specific, and surface-exposed peptide regions should serve as useful reagents for seroprevalence studies to better distinguish between prior infections with any of these mosquito-borne Flaviviruses. The development of better detection methods and diagnostic tools will enable clinicians and public health workers to more accurately estimate the true incidence rate of asymptomatic infections, neurological syndromes, and birth defects associated with ZIKV infection.

A rare case of aerococcus urinae infective endocarditis

ABSTRACTIntroduction: Aerococcus urinae is a rare cause of infective endocarditis. Aerococcus is a gram positive cocci that is easily misidentified as Staphylococci or Streptococci. The true incidence rate of this pathogen is likely underestimated. Recent advances in laboratory diagnostic methods with matrix-associated laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) have lead to increased recognition of this pathogen in the clinical microbiology lab, and awareness as a cause of infective endocarditis in the infectious disease community.Case reports: Aerococcus usually affects males with underlying urinary tract conditions. Herein, we report a case of prosthetic aortic valve endocarditis caused by Aerococcus urinae.Discussion: Our patient was considered high risk for cardiac surgery and was treated successfully with intravenous antibiotics alone for six weeks.Conclusion: Infective endocarditis should be considered in all cases of Aerococcus bacteremia and appropriate diagnostic evaluations pursued.Abbreviations: AV: Aortic valve; IE: Infective endocarditis

Estimation of chronic kidney disease incidence from prevalence and mortality data in American Indians with type 2 diabetes.

The objective was to estimate chronic kidney disease (CKD) incidence rates from prevalence and mortality data, and compare the estimates with observed (true) incidence rates in a well-characterized population with diabetes. Pima Indians aged 20 years and older with type 2 diabetes were followed from 1982 through 2007. CKD was defined by estimated GFR (eGFR) <60 ml/min/1.72 m2 or albumin-to-creatinine ratio (ACR) ≥30 mg/g. True CKD incidence and mortality rates were computed for the whole study period, and prevalence for the intervals 1982–1994 and 1995–2007. Estimated age-sex stratified CKD incidence rates were computed using illness-death models of the observed prevalences, and of the whole-period mortality rate ratio of CKD to non-CKD persons. Among 1201 participants, 616 incident events of CKD occurred during a median follow-up of 5.6 years. Observed CKD prevalence was 56.9% (95%CI 53.7–60.0) and 48.0% (95%CI 45.2–50.8) in women; 54.0% (95%CI 49.9–58.1) and 49.6% (95%CI 46.0–53.3) in men, across the two periods. Mortality rate was 2.5 (95%CI 1.9–3.3) times as high in women with CKD and 1.6 (95%CI 1.3–2.1) times as high in men with CKD, compared to women or men without CKD. In women, estimated CKD incidence increased linearly from 25.6 (95%CI 4.2–53.0) to 128.6 (95%CI 77.1–196.6) with each 5-year age group up to 69 years, and to 99.8 (95%CI 38.7–204.7) at age ≥70. In men, estimated CKD incidence increased form 28.5 (95%CI 3.8–71.2) at age 20–24 years to 118.7 (95%CI 23.6–336.7) at age ≥70. Age-sex-stratified estimated incidence reflected the magnitude and directional trend of the true incidence and were similar to the true incidence rates (p>0.05 for difference) except for age 20–24 in women (p = 0.008) and age 25–29 in men (p = 0.002). In conclusion, the estimated and observed incidence rates of CKD agree well over 25 years of observation in this well characterized population with type 2 diabetes.

First Presentation With Psychotic Symptoms in a Population-Based Sample.

Increasing evidence supports the effectiveness of comprehensive early intervention at first onset of psychotic symptoms. Implementation of early intervention programs will require population-based data on overall incidence of psychotic symptoms and on care settings of first presentation. In five large health care systems, electronic health records data were used to identify all first occurrences of psychosis diagnoses among persons ages 15-59 between January 1, 2007, and December 31, 2013 (N=37,843). For a random sample of these putative cases (N=1,337), review of full-text medical records confirmed clinician documentation of psychotic symptoms and excluded those with documented prior diagnosis of or treatment for psychosis. Initial incidence rates (based on putative cases) and confirmation rates (from record reviews) were used to estimate true incidence according to age and setting of initial presentation. Annual incidence estimates based on putative cases were 126 per 100,000 among those ages 15-29 and 107 per 100,000 among those ages 30-59. Rates of chart review confirmation ranged from 84% among those ages 15-29 diagnosed in emergency department or inpatient mental health settings to 19% among those ages 30-59 diagnosed in general medical outpatient settings. Estimated true incidence rates were 86 per 100,000 per year among those ages 15-29 and 46 per 100,000 among those ages 30-59. When all care settings were included, incidence of first-onset psychotic symptoms was higher than previous estimates based on surveys or inpatient data. Early intervention programs must accommodate frequent presentation after age 30 and presentation in outpatient settings, including primary care.

Accounting for reporting fatigue is required to accurately estimate incidence in voluntary reporting health schemes

ObjectiveAccurate estimation of the true incidence of ill-health is a goal of many surveillance systems. In surveillance schemes including zero reporting to remove ambiguity with nonresponse, reporter fatigue might increase the likelihood of a false zero case report in turn underestimating the true incidence rate and creating a biased downward trend over time. Study Design and SettingMultilevel zero-inflated negative binomial models were fitted to incidence case reports of three surveillance schemes running between 1996 and 2012 in the United Kingdom. Estimates of the true annual incidence rates were produced by weighting the reported number of cases by the predicted excess zero rate in addition to the within-scheme standard adjustment for response rate and the participation rate. ResultsTime since joining the scheme was associated with the odds of excess zero case reports for most schemes, resulting in weaker calendar trends. Estimated incidence rates (95% confidence interval) per 100,000 person years, were approximately doubled to 30 (21–39), 137 (116–157), 33 (27–39), when excess zero-rate adjustment was applied. ConclusionIf we accept that excess zeros are in reality nonresponse by busy reporters, then usual estimates of incidence are likely to be significantly underestimated and previously thought strong downward trends overestimated.

Providing Oral Nutrition to Women in Labor: American College of Nurse-Midwives.

Historically, oral intake for women during labor has been limited to nothing by mouth or clear liquids only. These restrictions are based on the risk of aspiration during or after the administration of general anesthesia. While aspiration can be life threatening, older methods of anesthesia are rarely used in current intrapartum care, and evidence is inconclusive that withholding oral nutrition reduces the risk of gastric aspiration. Additionally, withholding oral nutrition may result in the development of ketosis and may potentially contribute to a woman's stress and dissatisfaction with the birth experience. The purpose of this Clinical Bulletin is to review the evidence related to this practice and provide recommendations to promote informed, shared decision making regarding oral intake during labor with women at low risk for gastric aspiration.

Aneurisma da aorta abdominal – estudo epidemiológico de doentes tratados num centro por um período de 8 anos com o objetivo de promover o rastreio populacional

IntroductionThe rupture of an AAA is frequently fatal and accounts for nearly 1% of all deaths. Open surgical intervention is associated with high mortality, but EVAR (Endovascular Aneurysm Repair) is far from consensual owing to lack of level A evidence. Screening is cost effective in male patients over the age of 65 with a 44% reduction in AAA related mortality. This retrospective study had two endpoints, the first was the global assessment of care for both elective and urgent aneurysms in our institution. The second was raising awareness in local primary health care institutions for both the dismal prognosis of untreated AAA and the favorable prognosis of patients treated electively, using outcome data from our centre. MethodsData was extracted from the hospital database concerning urgent and elective repair of AAA from 2007 to 2014. ResultsOver the 8 year period, 155 elective aneurysm repairs were performed, 108 through open surgery and 47 through EVAR (with an increasing percentage with time). The early (30 days) mortality rate was 1.3%. We performed 51 aneurysm repairs for ruptured aneurysms (46 open surgery and 5 EVAR), with an intra‐operative mortality of 15.7% and early mortality of 47%. Concerning the geographic distribution of elective and urgent cases, we identified a tendency for assimetry in the distribution of elective and urgent repair of aneurysms. Unfortunately, due to lack of data concerning treatment of patients from our referral area in other centres and pre hospital mortality of ruptured aneurysms, no true incidence rates were possible to calculate. ConclusionsThe outcome of patients treated in our institution are comparable with data from literature We disclosed this data to all local primary health care institutions as well as the established recommendations for screening, with the final purpose of raising awareness for the active role they must have in the screening of AAA and treatment of this patients by controlling cardiovascular risk factors.

Trends in incidence for gestational trophoblastic disease over the last 20 years in a population-based study

BackgroundGestational trophoblastic disease (GTD) represents a heterogeneous group of disorders. Wide variations in incidence rates are reported worldwide, probably explained by a lack of centralized databases and heterogeneity in case definition. The aim of the present study was to determine the trends in incidence of GTD in the last 20years with the use of population-based data. Patients and methodsData on patients with pathologically confirmed diagnosis of GTD between 1994 and 2013 were obtained from PALGA, a nationwide archive containing all pathology reports in the Netherlands. ResultsIn the 20-year period 6343 cases were registered with GTD, representing an overall incidence rate of 1.67 per 1000 deliveries per year. An initial rise in incidence rate was seen over the first 10years (0.075 per year, 95% CI 0.040–0.109), followed by a stabilization from 2004 to 2013 (increase per year 0.011, 95% CI −0.017–0.040). Although partial hydatidiform mole (HM) was more common in earlier years, complete and partial HM reached comparable incidence rates of 0.68 and 0.64 per 1000 deliveries respectively from 2009 onwards. In the last decade, unspecified HM diagnosis declined significantly from 0.14 per 1000 deliveries in 2003 to 0.03 per 1000 deliveries (per year −0.011, CI −0.016–0.06), suggesting improved diagnostic analyses. ConclusionAfter an initial rise in GTD incidence in the Netherlands rates remained steady from 2004 onwards. As pathological confirmation is currently the norm and advanced pathological techniques are now widely available, true steady incidence rates may have been reached.

The role of principal and secondary diagnoses of hospitalized eye trauma: a nationwide cohort in Taiwan, 1996-2010.

PurposeTo estimate the rate of hospitalized eye trauma in Taiwan and investigate the role between principal and secondary diagnoses of such trauma.MethodsNationwide fixed cohort study of 1,000,000 beneficiaries from the Taiwan Longitudinal Health Database was used and 4819 patients who were hospitalized for eye trauma during 1996-2010 were analyzed.ResultsDuring 1996-2010, the incidence rates of hospitalized eye trauma (per 100 000 person-years) were 35.0 (95% confidence interval (CI), 34.0 to 36.0) for total diagnosis, 9.8 (95% CI, 9.3 to 10.3) for a principal diagnosis, and 25.3 (95% CI, 24.4 to 26.1) for a secondary diagnosis. The sex risk ratio was 3.1 for a principal diagnosis and 2.1 for a secondary diagnosis. The main causes of eye trauma were traffic accident, work accident, assault (among males <60 years of age), and falls (among elderly men and women). The proportion admitted to an ophthalmic department among those with a principal diagnosis of eye trauma (64.8%) was significantly higher than among those with a secondary diagnosis (2.3%) (p<.0001). Patients with a principal diagnosis of eye trauma had shorter hospital stays (7.1±10.2 days) and lower fatality (0.07%) than those with a secondary diagnosis of eye trauma (10.0±31.6 days and 0.3%, respectively).ConclusionData only from ophthalmic admissions tends to underestimate the true incidence rate of hospitalized eye trauma. Patients with a principal diagnosis of eye trauma had less severe injuries than did those with a secondary diagnosis.

English

Traumatic urinary bladder injuries in the recent times are considered to be of great importance in veterinary medicine, as they can lead to significant morbidity and subsequent mortality when diagnosed late or left untreated. However, the true incidence rates, absolute treatment recommendations and prognoses of lower urinary tract traumas are not available in literatures as the majority of specific information regarding lower urinary tract injuries in small animals exist as isolated case reports or small case series. Urologists may only encounter traumatic bladder injuries in their practice, because of the current modernization and human activities leading to increase in occurrence of the injuries. This paper reviews mainly the literatures and reports on the causes, clinical signs, diagnosis and management of traumatic urinary bladder injuries (blunt, penetrating and iatrogenic bladder traumas) to assist clinicians in this specialty. History, presenting clinical signs and laboratory evaluations are the diagnostic tools of bladder injuries and in predicting prognosis when treated. Despite presentation with nonspecific signs, haematuria and abdominal tenderness are the most common clinical signs of bladder rupture in animals. Early diagnosis and repair of bladder rupture offers good prognosis. Management of these conditions may require either solely medical or surgical intervention, while others will require a combined management intervention. &nbsp; Key words: Injuries, review, small animals, traumatic, urinary bladder.

Presumed Regional Incidence Rate of Out-of-Hospital Cardiac Arrest in Korea.

The regional incidence rates of out-of-hospital cardiac arrest (OHCA) were traditionally calculated with the residential population as the denominator. The aim of this study was to estimate the true incidence rate of OHCA and to investigate characteristics of regions with overestimated and underestimated OHCA incidence rates. We used the national OHCA database from 2006 to 2010. The nighttime residential and daytime transient populations were investigated from the 2010 Census. The daytime population was calculated by adding the daytime influx of population to, and subtracting the daytime outflow from, the nighttime residential population. Conventional age-standardized incidence rates (CASRs) and daytime corrected age-standardized incidence rates (DASRs) for OHCA per 100,000 person-years were calculated in each county. A total of 97,291 OHCAs were eligible. The age-standardized incidence rates of OHCAs per 100,000 person-years were 34.6 (95% CI: 34.3-35.0) in the daytime and 24.8 (95% CI: 24.5-25.1) in the nighttime among males, and 14.9 (95% CI: 14.7-15.1) in the daytime, and 10.4 (95% CI: 10.2-10.6) in the nighttime among females. The difference between the CASR and DASR ranged from 35.4 to -11.6 in males and from 6.1 to -1.0 in females. Through the Bland-Altman plot analysis, we found the difference between the CASR and DASR increased as the average CASR and DASR increased as well as with the larger daytime transient population. The conventional incidence rate was overestimated in counties with many OHCA cases and in metropolitan cities with large daytime population influx and nighttime outflow, while it was underestimated in residential counties around metropolitan cities.

Mechanisms of Immune Signaling in Colitis-Associated Cancer

The inflammatory bowel diseases ulcerative colitis and Crohn’s disease are associated with an increased risk for the development of colorectal cancer. During recent years, several immune signaling pathways have been linked to colitis-associated cancer (CAC), largely owing to the availability of suitable preclinical models. Among these, chronic intestinal inflammation has been shown to support tumor initiation through oxidative stress–induced mutations. A proinflammatory microenvironment that develops, possibly as a result of defective intestinal barrier function and host–microbial interactions, enables tumor promotion. Several molecular pathways such as tumor necrosis factor/nuclear factor-κB or interleukin 6/signal transducer and activator of transcription 3 signaling have been identified as important contributors to CAC development and could be promising therapeutic targets for the prevention and treatment of CAC.

A new method for assessing how sensitivity and specificity of linkage studies affects estimation.

BackgroundWhile the importance of record linkage is widely recognised, few studies have attempted to quantify how linkage errors may have impacted on their own findings and outcomes. Even where authors of linkage studies have attempted to estimate sensitivity and specificity based on subjects with known status, the effects of false negatives and positives on event rates and estimates of effect are not often described.MethodsWe present quantification of the effect of sensitivity and specificity of the linkage process on event rates and incidence, as well as the resultant effect on relative risks. Formulae to estimate the true number of events and estimated relative risk adjusted for given linkage sensitivity and specificity are then derived and applied to data from a prisoner mortality study. The implications of false positive and false negative matches are also discussed.DiscussionComparisons of the effect of sensitivity and specificity on incidence and relative risks indicate that it is more important for linkages to be highly specific than sensitive, particularly if true incidence rates are low. We would recommend that, where possible, some quantitative estimates of the sensitivity and specificity of the linkage process be performed, allowing the effect of these quantities on observed results to be assessed.