Mortality trends of amyotrophic lateral sclerosis in Norway 1951–2014: an age–period–cohort study

Recent studies suggest that the incidence and mortality of amyotrophic lateral sclerosis (ALS) are increasing. Changing environmental factors could influence disease risk differently throughout life span, and also between genders, birth cohorts, and seasons of birth. We aimed at describing long-term ALS mortality trends in Norway between 1951 and 2014 using age–period–cohort analysis. The Norwegian Cause of Death Registry provided ALS mortality data that were age- and sex-adjusted through direct standardization. Poisson regression analyses were used for identification of mortality trends and potential month of birth effects. We identified 5345 ALS cases, of which 54.7 % were men. ALS mortality increased throughout the whole period (p < 0.001), with a mean annual increase of 1.14 %. The increase was confined to those older than 60 years, but rates consistently dropped amongst the absolute oldest. The increase was mainly driven by birth cohort effects that increased from 1860 until 1934 (p < 0.001). No month of birth effect or change in sex ratio was found. The continuous increase in ALS mortality since 1951 is best explained by the long-term changes in exposure to risk factors or in case ascertainment, affecting men and women equally in the generations born since 1860 and at least into 1934.acceptedVersio

Bowel function and quality of life after superior mesenteric nerve plexus transection in right colectomy with D3 extended mesenterectomy

Background: The aim of this study was to ascertain the impact of injury to the superior mesenteric nerve plexus caused by right colectomy with D3 extended mesenterectomy as performed in the prospective multicenter trial: “Safe Radical D3 Right Hemicolectomy for Cancer through Preoperative Biphasic Multi-detector Computed Tomography” in which all soft tissue surrounding the superior mesenteric vessels from the level of the middle colic artery to that of the ileocolic artery was removed. Methods: Bowel function and gastrointestinal quality of life in two consecutive cohorts that underwent right colectomy with and without D3 extended mesenterectomy were compared. Main outcome measures were the Diarrhea Assessment Scale (DAS) and Gastrointestinal Quality of Life Index (GIQLI). The data were collected prospectively through telephone interviews. Results: Forty-nine patients per group, comparable for age, sex, length of bowel resected but with significantly shorter follow-up time in the experimental group, were included. There was no difference in total DAS scores, subscores or additional questions except for higher bowel frequency scores in the D3 group (p = 0.02). Comparison of total GIQLI scores and subscales showed no difference between groups. Regression analysis with correction for confounding factors showed 0.48 lower bowel frequency scores in the D2 group (p = 0.022). Within the D3 group presence of jejunal arteries cranial to the D3 dissection area showed 1.78 lower DAS scores and 0.7 lower bowel frequency scores. Conclusions: Small bowel denervation after right colectomy with D3 extended mesenterectomy leads to increased bowel frequency but does not impact gastrointestinal quality of life. Individual anatomical variants can affect postoperative bowel function differently despite standardized surgery.acceptedVersio

Sex ratio in multiple sclerosis mortality over 65 years; an age-period-cohort analysis in Norway

Increasing female: male ratio in multiple sclerosis (MS) has been assigned to cohort effects, with females in more recent birth cohorts possibly being more exposed or vulnerable to environmental risk factors than males. We collected MS mortality data in Norway from 1951 to 2015 from The Norwegian Cause of Death registry. Age-Period-Cohort analysis was conducted using log-linear Poisson models, including sex interaction terms. MS was registered as the underlying, contributing or direct cause in 6060 deaths. MS associated mortality remained stable with a slight preponderance among males until after 1980, and have since increased preferentially among females. Throughout the study period the mean annual increase was 1.25% for females and 0.3% for males (p < 0.0001). Age-period-cohort analysis revealed limited evidence of cohort effects for the gender differences; the best fitting model only included gender-age and gender-period interaction terms. The period effect evened out for males in the last three decades but increased for females, especially among the oldest age-groups. In conclusion, the increased female: male mortality ratio in MS associated mortality is driven mainly by increased mortality among females in the three last decades, particularly in the older age groups. It is best explained by disproportional period effects, providing evidence of time-varying external factors including improved access to diagnosis among females