Epidemiological similarities between appendicitis and diverticulitis suggesting a common underlying pathogenesis.

BACKGROUND: Nonperforating appendicitis is primarily a disease of children, and nonperforating diverticulitis affects mostly older adults. Apart from these age differences, the diseases share many epidemiological features, such as association with better hygiene and low-fiber diets. HYPOTHESIS: Nonperforating appendicitis and nonperforating diverticulitis are different manifestations of the same underlying colonic process and, if so, should be temporally related. DESIGN: Data from the National Hospital Discharge Survey were analyzed to investigate the incidence of admissions for appendicitis in children and diverticulitis in adults between 1979 and 2006. SETTING: Statistical sampling of all US hospitals. PATIENTS: Children admitted for appendicitis and adults with diverticulitis. MAIN OUTCOME MEASURES: Time trends were assessed for stationarity using unit root analysis, and similarities between time trends were tested using cointegration analysis. RESULTS: The incidence rates of nonperforating appendicitis and nonperforating diverticulitis exhibited U-shaped secular trends. The rates of perforating appendicitis and perforating diverticulitis rose slowly across all the study years. Cointegration analysis demonstrated that the rates of nonperforating and perforating diverticulitis did not cointegrate significantly over time. The rates of nonperforating and perforating appendicitis did not vary together. Nonperforating appendicitis and nonperforating diverticulitis rates were significantly cointegrated over time. CONCLUSIONS: Childhood appendicitis and adult diverticulitis seem to be similar diseases, suggesting a common underlying pathogenesis. Secular trends for their nonperforating and perforating forms are strikingly different. At least for appendicitis, perforating disease may not be an inevitable outcome from delayed treatment of nonperforating disease. If appendicitis represents the same pathophysiologic process as diverticulitis, it may be amenable to antibiotic rather than surgical treatment.

Effect of 11 September 2001 terrorist attacks in the USA on suicide in areas surrounding the crash sites.

BACKGROUND: The terrorist attacks in the USA on 11 September 2001 affected suicide rates in two European countries, whereas overall US rates remained stable. The effect on attack site rates, however, has not been studied. AIMS: To examine post-attack suicide rates in areas surrounding the three airline crash sites. METHOD: Daily mortality rates were modelled using time series techniques. Where rate change was significant, both duration and geographic scope were analysed. RESULTS: Around the World Trade Center, post-attack 180-day rates dropped significantly (t = 2.4, P = 0.0046), whereas comparison condition rates remained stable. No change was observed for Pentagon or Flight 93 crash sites. CONCLUSIONS: The differential effect by site suggests that proximity may be less important that other event characteristics. Both temporal and geographic aspects of rate fluctuation after sentinel events appear measurable and further analyses may contribute valuable knowledge about how sociological forces affect these rates.

Association of viral infection and appendicitis.

HYPOTHESIS: What causes appendicitis is not known; however, studies have suggested a relationship between viral diseases and appendicitis. Building on evidence of cyclic patterns of appendicitis with apparent outbreaks consistent with an infectious etiology, we hypothesized that there is a relationship between population rates of appendicitis and several infectious diseases. DESIGN: Epidemiologic study. SETTING: The National Hospital Discharge Survey PATIENTS: Estimated US hospitalized population. MAIN OUTCOME MEASURES: International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnosis codes of the National Hospital Discharge Survey were queried from 1970 to 2006 to identify admissions for appendicitis, influenza, rotavirus, and enteric infections. Cointegration analysis of time series data was used to determine if the disease incidence trends for these various disease entities varied over time together. RESULTS: Rates of influenza and nonperforating appendicitis declined progressively from the late 1970s to 1995 and rose thereafter, but influenza rates exhibited more distinct seasonal variation than appendicitis rates. Rotavirus infection showed no association with the incidence of nonperforating appendicitis. Perforating appendicitis showed a dissimilar trend to both nonperforating appendicitis and viral infection. Hospital admissions for enteric infections substantially increased over the years but were not related to appendicitis cases. CONCLUSIONS: Neither influenza nor rotavirus are likely proximate causes of appendicitis given the lack of a seasonal relationship between these disease entities. However, because of significant cointegration between the annual incidence rates of influenza and nonperforated appendicitis, it is possible that these diseases share common etiologic determinates, pathogenetic mechanisms, or environmental factors that similarly affect their incidence.

Disconnect between incidence of nonperforated and perforated appendicitis: implications for pathophysiology and management.

OBJECTIVE: Appendicitis has been declining in frequency for several decades. During the past 10 years, its preoperative diagnosis has been made more reliable by improved computed tomography (CT) imaging. Thresholds for surgical exploration have been lowered by the increased availability of laparoscopic exploration. These innovations should influence the number of appendectomies performed in the United States. We analyzed nationwide hospital discharge data to study the secular trends in appendicitis and appendectomy rates. METHODS: All appendicitis and appendiceal operations reported to the National Hospital Discharge Survey (NHDS) 1970-2004 were classified as perforated, nonperforated, negative, and incidental appendectomies and analyzed over time and by various demographic measures. Secular trends in the population-based incidence rates of nonperforated and perforated appendicitis and negative and incidental appendectomy were examined. RESULTS: Nonperforated appendicitis rates decreased between 1970 and 1995 but increased thereafter. The 25-year decreasing trend was accounted for almost entirely by a decreasing incidence in the 10-19 year age group. The rise after 1995 occurred in all age groups above 5 years and paralleled increasing rates of CT imaging and laparoscopic surgery on the appendix. Since 1995 the negative appendectomy rate has been falling, especially in women, and incidental appendectomies, frequent in prior decades, have been rarely performed. Despite these large changes, the rate of perforated appendicitis has increased steadily over the same period. Although perforated and nonperforated appendicitis rates were correlated in men, they were not significantly correlated in women nor were there significant negative correlations between perforated and negative appendectomy rates. CONCLUSION: The 25-year decline in nonperforated appendicitis and the recent increase in appendectomies coincident with more frequent use of CT imaging and laparoscopic appendectomies did not result in expected decreases in perforation rates. Similarly, time series analysis did not find a significant negative relationship between negative appendectomy and perforation rates. This disconnection of trends suggests that perforated and nonperforated appendicitis may have different pathophysiologies and that nonoperative management with antibiotic therapy may be appropriate for some initially nonperforated cases. Further efforts should be directed at identifying preoperative characteristics associated with nonperforating appendicitis that may eventually allow surgeons to defer operation for those cases of nonperforating appendicitis that have a low perforation risk.

Using a white matter reference to remove the dependency of global signal on experimental conditions in SPECT analyses.

Proportional scaling models are often used in functional imaging studies to remove confounding of local signals by global effects. It is generally assumed that global effects are uncorrelated with experimental conditions. However, when the global effect is estimated by the global signal, defined as the intracerebral average, incorrect inference may result from the dependency of the global signal on preexisting conditions or experimental manipulations. In this paper, we propose a simple alternative method of estimating the global effect to be used in a proportional scaling model. Specifically, by defining the global signal with reference strictly to a white matter region within the centrum semiovale, the dependency is removed in experiments where white matter is unaffected by the disease effect or experimental treatments. The increase in the ability to detect changes in regional blood flow is demonstrated in a SPECT study of healthy and ill Gulf War veterans in whom it is suspected that brain abnormalities influence the traditional calculation of the global signal. Controlling for the global effect, ill veterans have significantly lower intracerebral averages than healthy controls (P = 0.0038), evidence that choice of global signal has an impact on inference. Scaling by the modified global signal proposed here results in an increase in sensitivity leading to the identification of several regions in the insula and frontal cortex where ill veterans have significantly lower SPECT emissions. Scaling by the traditional global signal results in the loss of sensitivity to detect these regional differences. Advantages of this alternative method are its computational simplicity and its ability to be easily integrated into existing analysis frameworks such as SPM.

Improved agreement between Talairach and MNI coordinate spaces in deep brain regions.

Disagreement between the Talairach atlas and the stereotaxic space commonly used in software like SPM is a widely recognized problem. Others have proposed affine transformations to improve agreement in surface areas such as Brodmann's areas. This article proposes a similar transformation with the goal of improving agreement specifically in the deep brain region. The task is accomplished by finding an affine transformation that minimizes the mean distance between the surface coordinates of the lateral ventricles in the Talairach atlas and the MNI templates. The result is a transformation that improves deep brain agreement over both the untransformed Talairach coordinates and the surface-oriented transformation. While the transformation improves deep brain agreement, surface agreement is generally made worse. For areas near the lateral ventricle, the transformation presented herein is valuable for applications such as region of interest (ROI) modeling.