Trends in Abdominal Aortic and Iliac Aneurysm Repairs in Norway from 2001 to 2013.

OBJECTIVE/BACKGROUND: The objective was to examine trends in abdominal aortic and iliac aneurysm repairs in Norway from 2001 to 2013, and study regional variations and organizational developments in this type of vascular surgery. METHODS: This was a retrospective study on aortic and iliac aneurysm repairs using data from the Norwegian Patient Register. The vascular centers were categorized by yearly volume of repairs into small (<18), medium (18-49) and large (≥50). Incidence rates were assessed per 100,000 ≥ 60 years. The percentage of endovascular aneurysm repairs (EVAR) was calculated among the conducted repairs at the three categories of centers and the South-Eastern, Western, Central, and Northern Norway Regional Health Authority (NRHA). RESULTS: The national incidence rates of intact repairs per 100,000 ≥ 60 years increased from 57.4 to 65.7 (p < .01). Ruptured repairs decreased from 19.7 to 9.2 (p < .01). The rate of EVAR increased from 6.0 to 29.9 (p < .01) in intact and from 0.4 to 2.5 (p < .01) in ruptured repairs. The vascular centers were reduced from 25 to 16. The rate of EVAR was 27.1% (p < .01) higher at large centers and 7.9% (p < .03) higher at medium centers compared with small centers, and from 11.1% to 15.7% higher (p < .01) at the Central, Western, and Northern NRHA compared with the South-Eastern NRHA, which had the most centers (also in the large category). The national increase in intact EVAR from 10.6% to 43.3% was less compared with many other Western countries. CONCLUSION: During the study period the rates of intact repairs increased while the ruptured repairs decreased. EVAR was associated with centers performing high volumes of abdominal aortic and iliac aneurysm repairs and regional authorities organized with few centers.

Adaptation and constraint in a stickleback radiation.

The evolution of threespine sticklebacks in freshwater lakes constitutes a well-studied example of a phenotypic radiation that has produced numerous instances of parallel evolution, but the exact selective agents that drive these changes are not yet fully understood. We present a comparative study across 74 freshwater populations of threespine stickleback in Norway to test whether evolutionary changes in stickleback morphology are consistent with adaptations to physical parameters such as lake depth, lake area, lake perimeter and shoreline complexity, variables thought to reflect different habitats and feeding niches. Only weak indications of adaptation were found. Instead, populations seem to have diversified in phenotypic directions consistent with allometric scaling relationships. This indicates that evolutionary constraints may have played a role in structuring phenotypic variation across freshwater populations of stickleback. We also tested whether the number of lateral plates evolved in response to lake calcium levels, but found no evidence for this hypothesis.

Sibling-size variation in brown trout Salmo trutta in relation to egg size and stream size.

Sibling-size variation (SSV), estimated as the coefficient of variation of egg size, was investigated for 13 populations of brown trout Salmo trutta. SSV was negatively correlated with mean egg size both at the population and individual levels. After correction for the effect of mean egg size, SSV was also negatively correlated with stream size. These results provide new information about how salmonid SSV can vary at different ecological scales (individual, population and region). The results are discussed in light of competing theories for explaining SSV: (1) the passive effect hypothesis, stating that egg size variation follows passively from selection on egg size and (2) the bet-hedging hypothesis, stating that high SSV is adaptive in unpredictable environments.