Outbreak of Puumala Virus Infection, Sweden

An unexpected and large outbreak of Puumala virus infection in Sweden resulted in 313 nephropathia epidemica patients/100,000 persons in Västerbotten County during 2007. An increase in the rodent population, milder weather, and less snow cover probably contributed to the outbreak

Human Hantavirus Infections, Sweden

The prevalent human hantavirus disease in Sweden is nephropathia epidemica, which is caused by Puumala virus and shed by infected bank voles (Clethrionomys glareolus). To evaluate temporal and spatial patterns of this disease, we studied 2,468 reported cases from a highly disease-endemic region in northern Sweden. We found that, in particular, middle-aged men living in rural dwellings near coastal areas were overrepresented. The case-patients were most often infected in late autumn, when engaged in activities near or within manmade rodent refuges. Of 862 case-patients confident about the site of virus exposure, 50% were concentrated within 5% of the study area. The incidence of nephropathia epidemica was significantly correlated with bank vole numbers within monitored rodent populations in part of the region. Understanding this relationship may help forestall future human hantavirus outbreaks

Demographic Factors Associated with Hantavirus Infection in Bank Voles (Clethrionomys glareolus)

The bank vole (Clethrionomys glareolus) is the natural reservoir of Puumala virus (PUUV), a species in the genus Hantavirus. PUUV is the etiologic agent of nephropathia epidemica, a mild form of hemorrhagic fever with renal syndrome. Factors that influence hantavirus transmission within host populations are not well understood. We evaluated a number of factors influencing on the association of increased PUUV infection in bank voles captured in a region in northern Sweden endemic for the virus. Logistic regression showed four factors that together correctly predicted 80% of the model outcome: age, body mass index, population phase during sampling (increase, peak, or decline/low), and gender. This analysis highlights the importance of population demography in the successful circulation of hantavirus. The chance of infection was greatest during the peak of the population cycle, implying that the likelihood of exposure to hantavirus increases with increasing population density

Human immunoglobulin G levels of viruses and associated glioma risk

Few consistent etiological factors have been identified for primary brain tumors. Inverse associations to asthma and low levels of varicella-zoster virus, immunoglobulin (Ig) levels in prevalent cases have indicted a role for the immune system in the development of glioma. Because samples from prevalent cases of glioma could be influenced by treatments such as steroids and chemotherapy, we investigated pre-diagnostic samples from three large Scandinavian cohorts. To test the hypothesis that immune response levels to these viruses are associated etiologically with glioma risk, we investigated pre-diagnostic immunoglobulin levels for cytomegalovirus (CMV), varicella-zoster virus (VZV), adenovirus (Ad), and Epstein-Barr virus (EBV) including the nuclear antigen (EBNA1) using plasma samples from 197 cases of adult glioma and 394 controls collected from population-based cohorts in Sweden and Denmark. Low VZV IgG levels were marginally significantly more common in glioma cases than the controls (odds ratio (OR) = 0.68, 95% CI 0.41–1.13) for the fourth compared with the first quartile (p = 0.06 for trend). These results were more prominent when analyzing cases with blood sampling at least 2 years before diagnosis (OR = 0.63, 95% CI 0.37–1.08) (p = 0.03). No association with glioma risk was observed for CMV, EBV, and adenovirus

Epidemiology of Adult Ankle Fractures : 1756 cases identified in Norrbotten County during 2009–2013 and classified according to AO/OTA

Background: The ankle fracture is one of the most common fractures, increasing in an ageing population, but not generally seen as an osteoporotic fracture. The aim of this study was to examine the relationship between different AO/OTA classes of ankle fractures, age, sex and type of trauma. Methods: Ankle fractures, treated at any of the hospitals in Norrbotten County in Sweden between 2009 and 2013, were retrospectively identified and classified according to the AO/OTA-classification system. Information about the trauma mechanism was also obtained. Results: In Norrbotten County, 1756 ankle fractures in 1735 patients aged 20 years or older were identified. This gave an incidence in the county of 179 per 100,000 person-years. Of these patients, 34.6% were 65 years or older, 58.4% were women and 68.2% of the trauma leading to a fracture was defined as low-energy. In 1.5% of the cases the fractures were open. Incidences of type B fractures increased substantially with age, from 62 (95% CI 50–77) at 30–39 years of age to 158 (95% CI 131–190) in patients older than 80 years of age per 100,000 person-years. Type B fractures showed a slightly higher proportion of low-energy trauma while type C showed a lower mean age and proportion of women. Conclusions: This study shows an incidence of 179 adult ankle fractures annually per 100,000 persons. More than two thirds of the fractures were caused by a low-energy trauma and ankle fractures are more frequent among females. Females generally have an increased incidence during their life, mainly between the ages of 30 and 60. This is in contrast to men who have more of an even distribution throughout their life. Classification according to AO/OTA reveals some heterogeneity among the classes of ankle fractures in age and gender as well as the energy involved in the trauma

Routine use of LMWH prophylaxis is associated with a lower incidence of venous thromboembolic events following an ankle fracture

Background: Venous thromboembolic events (VTE) are well-known and serious complications following a trauma to the lower extremities. There is an ongoing debate on the benefit of low-molecular-weight heparin (LMWH) as prophylaxis following ankle fracture treatment. We examined the association between the incidence of VTE and the use of LMWH-prophylaxis following an ankle fracture, as well as factors affecting the risk of VTE. Methods: In this retrospective cohort study, data on ankle fractures and fracture treatment from the Swedish Fracture Register was linked to data from the Swedish National Patient Register and the Swedish Prescribed Drug Register. Patients with VTE and patients who received LMWH prophylaxis were identified. The treating orthopedic departments were sent a questionnaire about their guidelines regarding the use of LMWH prophylaxis. Results: 222 cases of diagnosed VTE were identified among 14,954 ankle fractures. Orthopedic departments with higher-than-average use of LMWH prophylaxis among non-operatively treated ankle fractures had a lower incidence of VTE (OR 0.60, CI 0.39–0.92). Among operatively treated patients, departments with a guideline for the routine use of LMWH prophylaxis also had lower incidence of VTE (OR 0.56, CI 0.37–0.86). A later onset of VTE was seen among patients prescribed LMWH prophylaxis, with a mean of 56 days to onset (CI 44–67), compared to 39 days (CI 33–45) in patients without prescribed prophylaxis. During the first two weeks following injury, there was only one case of VTE in patients with prescribed LMWH, compared to 39 cases of VTE among patients without prescribed prophylaxis. Conclusions: Routine use of LMWH in patients with operatively treated ankle fractures was associated with a lower incidence of VTE. A more frequent use of LMWH among patients with non-operatively treated ankle fractures were associated with a lower incidence of VTE. The onset occurred later among patients with LMWH-prophylaxis who still suffered a VTE

Evaluating non-responders of a survey in the Swedish fracture register : no indication of different functional result

Background: The Swedish Fracture Register (SFR) currently contains information on more than 190,000 fractures. Patient Reported Outcome Measures (PROMs) are used for monitoring functional results after fracture treatment. One weakness, as in many surveys, is a low response rate. The aim of the current study was to examine if non-responders of a survey in the SFR differ in PROMs scores, how age and gender influence the response rate and reasons for not responding. Methods: Patients with fractures of radius, ulna or humerus between June and August 2013 and registered in the SFR were included in the study. The non-responders to both the pre-injury and the 1-year survey were contacted by phone and reminded to reply. A comparison of the results of both EQ-5D and Short Musculoskeletal Function Assessment (SMFA) could be made between the responders after a phone reminder and the initial responders. The response rate for the register as a whole was extracted in order to identify how age and gender affect the response rate. Results: Three hundred seventeen of the patients included in the study responded initially. After phone reminder another 94 patients answered the pre-injury survey. Two hundred sixty eight responded initially to the 1-year follow-up survey and 42 after phone reminder. No significant difference was identified in the score of the pre-injury survey between initial responders and responders after phone reminder neither in the EQ-5D nor in the Short Musculoskeletal Function Assessment (SMFA). Regarding the 1-year survey, responders after a phone reminder reported a significantly better outcome in crude data of SMFA score. This difference disappeared after controlling for confounding factors through case control matching. The highest response rate to PROMs in the SFR was among females in the age range 60-69 years. Conclusion: This study indicates that both in the preinjury survey as well as in the 1-year survey the non-responders in the SFR report similar function compared to the initial responders. Age and gender of patients affect the response rate of the survey which needs to be taken into consideration in analysis of data from the SFR

Substantial accuracy of fracture classification in the Swedish Fracture Register : evaluation of AO/OTA-classification in 152 ankle fractures

Introduction: Since 2011 the Swedish Fracture Register (SFR) has collected information on fracture epidemiology, treatment and outcome. More than 112 000 fractures, including 11 600 ankle fractures, have been registered so far. The accuracy of the classification is crucial when using the register in future research and quality improvement of care. In this study we examine the degree of accuracy of the AO/ OTA-classification in which ankle fractures are recorded in the SFR. Methods: 152 randomly selected ankle fractures registered in the SFR were classified independently by a reference group of three orthopedic surgeons on two occasions. The agreed AO/OTA-classification of the reference group was regarded as the gold standard classification for each case. The originally recorded classification in the SFR was subsequently compared with the classification of the reference group and accuracy calculated. Results: The agreement between the classification in the SFR and of the reference group was 74%, corresponding to kappa 0.67, 95% CI (0.58-0.76) for AO/OTA group level. An agreement of 88% equivalent to kappa 0.77, 95% CI (0.67-0.87) was noted for AO/OTA type level. The agreement corresponds to substantial according to Landis and Koch. The kappa value of inter-and intraobserver agreement ranged from 0.67 to 0.93. Conclusions: The study results show substantial agreement between classifications made in the SFR and gold standard classification. The finding is equivalent to or higher than in previous studies. Consequently, we conclude that classifications of ankle fractures in the SFR are accurate and valid