| 1. |
- Lu, Yunxia, et al.
(författare)
-
Anthropometry-based obesity phenotypes and risk of colorectal adenocarcinoma : a large prospective cohort study in Norway
- 2016
-
Ingår i: Epidemiology. - Stockholm : Karolinska Institutet, Dept of Molecular Medicine and Surgery. - 1044-3983. ; 27:3, s. 423-432
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It is unclear whether obesity phenotypes measured by different anthropometric indices are associated with a risk of colorectal adenocarcinoma by anatomical location. METHODS: We compiled harmonized population-based cohort studies (Cohort of Norway, CONOR) with 143,477 participants that were conducted between 1994 and 2010. General, abdominal, and gluteofemoral obesity were assessed by body mass index (BMI, kg/m(2)), waist circumference (cm), and hip circumference (cm). Other measures examined were waist to hip ratio, waist to height ratio, and body adiposity index. We performed Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of obesity relative to a risk of colorectal adenocarcinoma. RESULTS: In total, 2,044 incident cases of colorectal adenocarcinoma were identified. We observed a positive association between waist circumference (high versus low) and adenocarcinoma in the proximal colon (HR = 1.9, 95% CI = 1.5, 2.5) and distal colon (HR = 1.7, 95% CI = 1.3, 2.3) when adjusted for BMI. The association with waist circumference was especially strong in men. BMI was not associated with adenocarcinoma in the colon or rectum after adjusting for waist circumference. We found no association between hip circumference and colorectal adenocarcinoma. When adjusted for BMI plus waist circumference, body adiposity index was negatively associated with adenocarcinoma in the proximal or distal colon. CONCLUSION: Abdominal obesity, but not general or gluteofemoral obesity, was associated with an increased risk of adenocarcinoma in the proximal and the distal colon, especially in men. Muscularity may be negatively associated with risk of colon adenocarcinoma.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Ahlbom, Anders, et al.
(författare)
-
Occupational magnetic field exposure and myocardial infarction incidence.
- 2004
-
Ingår i: Epidemiology. - : Ovid Technologies (Wolters Kluwer Health). - 1044-3983 .- 1531-5487. ; 15:4, s. 403-8
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Studies on healthy volunteers have seen reduced heart rate variability after exposure to extremely low-frequency electric and magnetic fields (EMF). Because reduced heart rate variability has been linked to cardiovascular disease risk, it has been hypothesized that exposure to EMF might increase the risk of cardiovascular disease. One epidemiologic study has shown increased mortality from cardiovascular conditions in utility workers with elevated exposure to magnetic fields, but several other epidemiologic studies have failed to confirm this result. We tested the hypothesis that occupational EMF exposure increases the risk of myocardial infarction in a large population-based case-control study of myocardial infarction, with detailed information on potential confounders. METHODS: We used data from the SHEEP study, which is a population-based case-control study of acute myocardial infarction in Stockholm. Occupational EMF exposure was based on job titles 1, 5, and 10 years before diagnosis. We used 2 approaches to classify exposure: first, specific individual job titles with presumed elevated EMF exposure, and second, classification of subjects according to a job-exposure matrix. RESULTS: We found no increased risk of myocardial infarction in subjects classified as having elevated EMF exposure. For the highest exposure category of > or = 0.3 microT according to the job-exposure matrix, the adjusted relative risk was = 0.57 (95% confidence interval = 0.36-0.89). CONCLUSIONS: The results of this study do not support the hypothesis that occupational EMF exposure increases the risk of myocardial infarction.
|
|
| 6. |
|
|
| 7. |
- Ahlsson, Fredrik, 1967-, et al.
(författare)
-
School Performance After Preterm Birth
- 2015
-
Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 26:1, s. 106-111
-
Tidskriftsartikel (refereegranskat)abstract
- Background: An increased risk of poor school performance for children born preterm has been shown in many studies, but whether this increase is attributable to preterm birth per se or to other factors associated with preterm birth has not been resolved. Methods: We used data from the Swedish Medical Birth Register, the Longitudinal Integration Database for Sickness Insurance and Labor Market Study, the Swedish Multigeneration Register, and the National School Register to link records comprising the Swedish birth cohorts from 1974 through 1991. Linear regression was used to assess the association between gestational duration and school performance, both with and without controlling for parental and socioeconomic factors. In a restricted analysis, we compared siblings only with each other. Results: Preterm birth was strongly and negatively correlated with school performance. The distribution of school grades for children born at 31-33 weeks was on average 3.85 (95% confidence interval = -4.36 to -3.35) centiles lower than for children born at 40 weeks. For births at 22-24 weeks, the corresponding figure was -23.15 (-30.32 to -15.97). When taking confounders into account, the association remained. When restricting the analysis to siblings, however, the association between school performance and preterm birth after week 30 vanished completely, whereas it remained, less pronounced, for preterm birth before 30 weeks of gestation. Conclusions: Our study suggests that the association between school performance and preterm birth after 30 gestational weeks is attributable to factors other than preterm birth per se.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Alping, Peter, et al.
(författare)
-
Validation of the Swedish Multiple Sclerosis Register Further Improving a Resource for Pharmacoepidemiologic Evaluations
- 2019
-
Ingår i: Epidemiology. - : Lippincott Williams & Wilkins. - 1044-3983 .- 1531-5487. ; 30:2, s. 230-233
-
Tidskriftsartikel (refereegranskat)abstract
- The Swedish Multiple Sclerosis Register is a national register monitoring treatment and clinical course for all Swedish multiple sclerosis (MS) patients, with high coverage and close integration with the clinic. Despite its great value for epidemiologic research, it has not previously been validated. In this brief report, we summarize a large validation of >3,000 patients in the register using clinical chart review in the context of the COMBAT-MS study. While further improving the data quality for a central cohort of patients available for future epidemiologic research, this study also allowed us to estimate the accuracy and completeness of the register data.
|
|
| 14. |
- Aström, Daniel Oudin, et al.
(författare)
-
Acute Fatal Effects of Short-Lasting Extreme Temperatures in Stockholm, Sweden : Evidence Across a Century of Change.
- 2013
-
Ingår i: Epidemiology. - : Lippincott Williams & Wilkins. - 1044-3983 .- 1531-5487. ; 24:6, s. 820-829
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Climate change is projected to increase the frequency of extreme weather events. Short-term effects of extreme hot and cold weather and their effects on mortality have been thoroughly documented, as have epidemiologic and demographic changes throughout the 20th century. We investigated whether sensitivity to episodes of extreme heat and cold has changed in Stockholm, Sweden, from the beginning of the 20th century until the present.METHODS: We collected daily mortality and temperature data for the period 1901-2009 for present-day Stockholm County, Sweden. Heat extremes were defined as days for which the 2-day moving average of mean temperature was above the 98th percentile; cold extremes were defined as days for which the 26-day moving average was below the 2nd percentile. The relationship between extreme hot/cold temperatures and all-cause mortality, stratified by decade, sex, and age, was investigated through time series modeling, adjusting for time trends.RESULTS: Total daily mortality was higher during heat extremes in all decades, with a declining trend over time in the relative risk associated with heat extremes, leveling off during the last three decades. The relative risk of mortality was higher during cold extremes for the entire period, with a more dispersed pattern across decades. Unlike for heat extremes, there was no decline in the mortality with cold extremes over time.CONCLUSIONS: Although the relative risk of mortality during extreme temperature events appears to have fallen, such events still pose a threat to public health.
|
|
| 15. |
|
|
| 16. |
- Axelson, Olav, 1937-, et al.
(författare)
-
Leukemia in childhood and adolescence and exposure to ionizing radiation in homes built from uranium-containing alum shale concrete
- 2002
-
Ingår i: Epidemiology. - : Ovid Technologies (Wolters Kluwer Health). - 1044-3983 .- 1531-5487. ; 13:2, s. 146-150
-
Tidskriftsartikel (refereegranskat)abstract
- Concerns in Sweden about indoor radon around 1980 prompted measurements of gamma-radiation from the facades of houses to identify those constructed of uranium-containing alum shale concrete, with potentially high radon concentrations. To evaluate any possible risk of acute lymphocytic leukemia from exposure to elevated gamma-radiation in these homes, we identified the acute lymphocytic leukemia cases less than 20 years of age in Sweden during 1980-1989 as well as eight controls per case from the population registry, matching on age, gender, and county. Using the existing measurements, exposure was assessable for 312 cases and 1,418 controls from 151 properly measured municipalities. A conditional logistic odds ratio of 1.4 (95% confidence interval = 1.0-1.9) was obtained for those ever having lived in alum shale concrete houses, with the average exposure exceeding 0.10 microsieverts per hour. Comparing those who ever lived in alum shale concrete houses (divided by higher and lower annual average exposure) with those who never lived in such houses, we found a weak dose-response relation. The results suggest some risk of acute lymphocytic leukemia from indoor ionizing radiation among children and young adults.
|
|
| 17. |
|
|
| 18. |
- Baste, Valborg, et al.
(författare)
-
Prospective study of pregnancy outcomes after parental cell phone exposure : the Norwegian mother and child cohort study
- 2015
-
Ingår i: Epidemiology. - 1044-3983. ; 26:4, s. 613-621
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Research about prenatal exposure to electromagnetic fields from cell phones among expectant parents and reproductive outcome is limited. The aim of this article is to investigate the association between pregnancy outcome and parental cell phone exposure in a large prospective study. Methods: The study was based on the Norwegian Mother and Child Cohort Study conducted during the decade 1999–2009. In that study, pregnant women were recruited before a routine ultrasound examination during gestational week 15; they answered a questionnaire at that time and again around gestational week 30. The expectant father was invited to answer a questionnaire during gestational week 15 (2001–2009). The forms contained questions regarding cell phone use. The response rate was 38.7% and the cohort comprised 100,730 singleton births. Pregnancy outcomes were obtained by linkage to the Medical Birth Registry of Norway. Results: The risk of preeclampsia was slightly lower among women with medium and high cell phone exposure compared with low exposure after adjusting for potential confounders. Fathers with testis exposure when using cell phones had a borderline increased risk of perinatal mortality among offspring and a slightly decreased risk of partner developing preeclampsia during pregnancy compared with no cell phone exposure of head or testis. None of the other pregnancy outcomes was associated with cell phone exposure. Conclusions: We found no association between maternal prenatal or paternal preconceptional cell phone exposure and any of the studied pregnancy outcomes. The only risk estimate suggesting a potential increased risk was not consistent with other findings.
|
|
| 19. |
|
|
| 20. |
- Beelen, Rob, et al.
(författare)
-
Long-term Exposure to Air Pollution and Cardiovascular Mortality An Analysis of 22 European Cohorts
- 2014
-
Ingår i: Epidemiology. - : Lippincott Williams & Wilkins. - 1044-3983 .- 1531-5487. ; 25:3, s. 368-378
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Air pollution has been associated with cardiovascular mortality, but it remains unclear as to whether specific pollutants are related to specific cardiovascular causes of death. Within the multicenter European Study of Cohorts for Air Pollution Effects (ESCAPE), we investigated the associations of long-term exposure to several air pollutants with all cardiovascular disease (CVD) mortality, as well as with specific cardiovascular causes of death. Methods: Data from 22 European cohort studies were used. Using a standardized protocol, study area-specific air pollution exposure at the residential address was characterized as annual average concentrations of the following: nitrogen oxides (NO2 and NOx); particles with diameters of less than 2.5 mu m (PM2.5), less than 10 mu m (PM10), and 10 mu m to 2.5 mu m (PMcoarse); PM2.5 absorbance estimated by land-use regression models; and traffic indicators. We applied cohort-specific Cox proportional hazards models using a standardized protocol. Random-effects meta-analysis was used to obtain pooled effect estimates. Results: The total study population consisted of 367,383 participants, with 9994 deaths from CVD (including 4,992 from ischemic heart disease, 2264 from myocardial infarction, and 2484 from cerebrovascular disease). All hazard ratios were approximately 1.0, except for particle mass and cerebrovascular disease mortality; for PM2.5, the hazard ratio was 1.21 (95% confidence interval = 0.87-1.69) per 5 mu g/m(3) and for PM10, 1.22 (0.91-1.63) per 10 mu g/m(3). Conclusion: In a joint analysis of data from 22 European cohorts, most hazard ratios for the association of air pollutants with mortality from overall CVD and with specific CVDs were approximately 1.0, with the exception of particulate mass and cerebrovascular disease mortality for which there was suggestive evidence for an association.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
- Bero Bedada, Getahun, et al.
(författare)
-
Short-term Exposure to Ozone and Mortality in Subjects With and Without Previous Cardiovascular Disease
- 2016
-
Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 27:5, s. 663-669
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Exposure to ground level ozone (O3) is a public health problem associated with a range of risks across population subgroups. Our aim was to investigate the role of previous cardiovascular diseases (CVDs) in mortality related to short-term O3 exposure.METHODS: Deaths between 1990 and 2010 in Stockholm County were matched with previous hospitalizations in Swedish registries. An urban background monitoring station provided hourly values of air quality data, from which we calculated 8-hour running averages and daily 8-hour maximum. We analyzed associations between daily O3 concentrations and mortality among persons with and without previous CVD hospitalization with a generalized additive model adjusted for time trend, influenza, and weather. We also performed two-pollutant models.RESULTS: There were 302,283 nontrauma-related deaths, out of which 196,916 had previous CVD hospitalization. The mean concentration of daily maximum 8-hour O3 was 62.9 μg/m. An average 10 μg/m increase in the same and preceding day was associated with an increased mortality of 1.72% (95% confidence interval: 0.44%, 3.02%) in those with prior admission for acute myocardial infarction (AMI), which was more than three times higher than for those with no previous AMI (0.50, 95% confidence interval: 0.10%, 0.89%, P value for interaction 0.098). The association between O3 and mortality remained essentially unchanged in two-pollutant models with NO2, NOx, and PM10.CONCLUSIONS: Our study indicates that short-term exposure to O3 is associated with increased mortality in those with a previous hospitalization for AMI.
|
|
| 29. |
- Bigert, Carolina, et al.
(författare)
-
Myocardial infarction among professional drivers.
- 2003
-
Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 14:3, s. 333-9
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Professional drivers are at an increased risk of myocardial infarction but the underlying causes for this increased risk are uncertain. METHODS: We identified all first events of myocardial infarction among men age 45-70 years in Stockholm County for 1992 and 1993. We selected controls randomly from the population. Response rates of 72% and 71% resulted in 1067 cases and 1482 controls, respectively. We obtained exposure information from questionnaires. We calculated odds ratios (ORs), with and without adjustment for socioeconomic status, tobacco smoking, alcohol drinking, physical inactivity at leisure time, overweight status, diabetes and hypertension. RESULTS: The crude OR among bus drivers was 2.14 (95% confidence interval = 1.34-3.41), among taxi drivers 1.88 (1.19-2.98) and among truck drivers 1.66 (1.22-2.26). Adjustment for potential confounders gave lower ORs: 1.49 (0.90-2.45), 1.34 (0.82-2.19) and 1.10 (0.79-1.53), respectively. Additional adjustment for job strain lowered the ORs only slightly. An exposure-response pattern (by duration of work) was found for bus and taxi drivers. CONCLUSIONS: The high risk among bus and taxi drivers was partly explained by unfavorable life-style factors and social factors. The work environment may contribute to their increased risk. Among truck drivers, individual risk factors seemed to explain most of the elevated risk.
|
|
| 30. |
- Bijlsma, Maarten J., et al.
(författare)
-
The Impact of Unemployment on Antidepressant Purchasing : Adjusting for Unobserved Time-constant Confounding in the g-Formula
- 2019
-
Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 30:3, s. 388-395
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The estimated effect of unemployment on depression may be biased by time-varying, intermediate, and time-constant confounding. One of the few methods that can account for these sources of bias is the parametric g-formula, but until now this method has required that all relevant confounders be measured.Methods: We combine the g-formula with methods to adjust for unmeasured time-constant confounding. We use this method to estimate how antidepressant purchasing is affected by a hypothetical intervention that provides employment to the unemployed. The analyses are based on an 11% random sample of the Finnish population who were 30–35 years of age in 1995 (n = 49,753) and followed until 2012. We compare estimates that adjust for measured baseline confounders and time-varying socioeconomic covariates (confounders and mediators) with estimates that also include individual-level fixed-effect intercepts.Results: In the empirical data, around 10% of person-years are unemployed. Setting these person-years to employed, the g-formula without individual intercepts found a 5% (95% confidence interval [CI] = 2.5%, 7.4%) reduction in antidepressant purchasing at the population level. However, when also adjusting for individual intercepts, we find no association (−0.1%; 95% CI = −1.8%, 1.5%).Conclusions: The results indicate that the relationship between unemployment and antidepressants is confounded by residual time-constant confounding (selection). However, restrictions on the effective sample when using individual intercepts can compromise the validity of the results. Overall our approach highlights the potential importance of adjusting for unobserved time-constant confounding in epidemiologic studies and demonstrates one way that this can be done.
|
|
| 31. |
|
|
| 32. |
- Bluhm, G, et al.
(författare)
-
Road traffic noise and hypertension
- 1999
-
Ingår i: EPIDEMIOLOGY. - 1044-3983. ; 10:4, s. S141-S141
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 33. |
|
|
| 34. |
- Bodin, L., et al.
(författare)
-
The association of shift work and nitrous oxide exposure in pregnancy with birth weight and gestational age
- 1999
-
Ingår i: Epidemiology. - 1044-3983. ; 10:4, s. 429-36
-
Tidskriftsartikel (refereegranskat)abstract
- We examined the relation between shift work and occupational nitrous oxide exposure in the second trimester of pregnancy and birth weight and gestational age at delivery among the members of the Swedish Midwives Association. Eighty-four per cent of members who were registered in 1989 responded to a postal questionnaire concerning occupational exposures, including work schedule and the use of nitrous oxide, in relation to each of their pregnancies. We obtained information on births from the Swedish Medical Birth Register. We used models with allowance for dependence between births for the same woman and found that night work was associated with preterm birth (<37 weeks) [odds ratio (OR) = 5.6; 95% confidence limits (CL) = 1.9, 16.4] and to a lesser extent with low birth weight [OR = 1.9 (95% CL = 0.6, 5.8)]. Three-shift work schedule (day, evening, and night rotation) showed a possible association with preterm birth [OR = 2.3 (95% CL = 0.7, 7.3)]. Exposure to nitrous oxide use was associated with reduced birth weight (-77 gm; 95% CL = -129, -24) and an increase in the odds of infants being small for gestational age (< or = 10th percentile of weight for gestational week) (OR = 1.8; 95% CL = 1.1, 2.8).
|
|
| 35. |
|
|
| 36. |
|
|
| 37. |
|
|
| 38. |
|
|
| 39. |
|
|
| 40. |
- Bonander, Carl, et al.
(författare)
-
A Capture-Recapture-based Ascertainment Probability Weighting Method for Effect Estimation With Under-ascertained Outcomes.
- 2024
-
Ingår i: Epidemiology (Cambridge, Mass.). - : Lippincott Williams & Wilkins. - 1531-5487 .- 1044-3983. ; 35:3, s. 340-348
-
Tidskriftsartikel (refereegranskat)abstract
- Outcome under-ascertainment, characterized by the incomplete identification or reporting of cases, poses a substantial challenge in epidemiologic research. While capture-recapture methods can estimate unknown case numbers, their role in estimating exposure effects in observational studies is not well established. This paper presents an ascertainment probability weighting framework that integrates capture-recapture and propensity score weighting. We propose a nonparametric estimator of effects on binary outcomes that combines exposure propensity scores with data from two conditionally independent outcome measurements to simultaneously adjust for confounding and under-ascertainment. Demonstrating its practical application, we apply the method to estimate the relationship between health care work and coronavirus disease 2019 testing in a Swedish region. We find that ascertainment probability weighting greatly influences the estimated association compared to conventional inverse probability weighting, underscoring the importance of accounting for under-ascertainment in studies with limited outcome data coverage. We conclude with practical guidelines for the method's implementation, discussing its strengths, limitations, and suitable scenarios for application.
|
|
| 41. |
- Bonander, Carl
(författare)
-
A (Flexible) Synthetic Control Method for Count Data and Other Nonnegative Outcomes
- 2021
-
Ingår i: Epidemiology. - : Ovid Technologies (Wolters Kluwer Health). - 1044-3983. ; 32:5, s. 653-660
-
Tidskriftsartikel (refereegranskat)abstract
- The synthetic control method is a covariate balancing method that exploits data from untreated regions to construct a synthetic control that approximates a single, aggregate treatment unit on a time series of preintervention outcomes and covariates. The method is increasingly being used to evaluate population-level interventions in epidemiology. Although the original version can be used with bounded outcomes, it imposes strong constraints on the balancing weights to ensure that the counterfactuals are based solely on interpolation. This feature, while attractive from a causal inference perspective, is sometimes too conservative and can lead to unnecessary bias due to poor covariate balance. Alternatives exist that allow for extrapolation to improve balance but existing procedures may produce negative estimates of the counterfactual outcomes and are therefore inappropriate for count data. We propose an alternative way to allow for extrapolation, although ensuring that the estimated counterfactuals remain nonnegative. Following a related proposal, we add a penalty to the balancing procedure that favors interpolation over extrapolation whenever possible. As we demonstrate theoretically and using empirical examples, our proposal can serve as a useful alternative when existing approaches yield demonstrably poor or unrealistic counterfactuals. Finally, we provide functions to implement the method in R.
|
|
| 42. |
|
|
| 43. |
|
|
| 44. |
- Bornman, Riana, et al.
(författare)
-
DDT in Brest Milk: Intake, Risk, Lactation Duration, and Effect of Gender.
- 2012
-
Ingår i: Epidemiology. - : Ovid Technologies (Wolters Kluwer Health). - 1044-3983.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- DDT is annually applied indoors of every dwelling at 64-128 g DDT for malaria vector control. We studied 163 breast milk samples from three DDT-sprayed villages and one reference village in South Africa for the presence and levels of DDT. Mean ?DDT levels in breast milk from the DDT-sprayed villages were 18, 11, and 9.5 mg/kg mf (milk fat) (1.4 mg/kg mf reference village). Primipara mothers from DDT-sprayed villages had significantly higher levels ?DDT in their milk. The highest DDT level in breast milk ever reported from South Africa was detected (5.2 mg/l wm (whole milk) and 140 mg/kg mf). The Maximum Residue Limit (MRL) in milk and Provisional Tolerable Daily Intake (PTDI) for DDT by infants were significantly exceeded in DDT-sprayed villages (maximum exceeded the MRL 310 times, and the PTDI 99 times). The differences between villages indicated differences in exposure and uptake due to application, substrate, and/or culture. The duration of completed lactation was similar for all four villages and DDT exposure had no effect on the duration. There were indications (not significant) that first-born female infants drank milk with higher ?DDT levels than first-born male infants and vice versa for multipara male and female infants. These patterns were evident in each of the DDT-spayed villages, suggesting gender involvement on levels of DDT in breast milk. In view of the high levels recorded, effective measures to reduce DDT exposure are urgently needed, over and above the need to find suitable, safe, and sustainable alternatives.
|
|
| 45. |
|
|
| 46. |
|
|
| 47. |
- Burgess, Stephen, et al.
(författare)
-
Sensitivity Analyses for Robust Causal Inference from Mendelian Randomization Analyses with Multiple Genetic Variants
- 2017
-
Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 28:1, s. 30-42
-
Forskningsöversikt (refereegranskat)abstract
- Mendelian randomization investigations are becoming more powerful and simpler to perform, due to the increasing size and coverage of genome-wide association studies and the increasing availability of summarized data on genetic associations with risk factors and disease outcomes. However, when using multiple genetic variants from different gene regions in a Mendelian randomization analysis, it is highly implausible that all the genetic variants satisfy the instrumental variable assumptions. This means that a simple instrumental variable analysis alone should not be relied on to give a causal conclusion. In this article, we discuss a range of sensitivity analyses that will either support or question the validity of causal inference from a Mendelian randomization analysis with multiple genetic variants. We focus on sensitivity analyses of greatest practical relevance for ensuring robust causal inferences, and those that can be undertaken using summarized data. Aside from cases in which the justification of the instrumental variable assumptions is supported by strong biological understanding, a Mendelian randomization analysis in which no assessment of the robustness of the findings to violations of the instrumental variable assumptions has been made should be viewed as speculative and incomplete. In particular, Mendelian randomization investigations with large numbers of genetic variants without such sensitivity analyses should be treated with skepticism.
|
|
| 48. |
- Bälter, Katarina, et al.
(författare)
-
Web-based and mailed questionnaires : A comparison of response rates and compliance
- 2005
-
Ingår i: Epidemiology. - Karolinska Inst, Dept Med Epidemiol & Biostat, SE-17177 Stockholm, Sweden. : Ovid Technologies (Wolters Kluwer Health). - 1044-3983 .- 1531-5487. ; 16:4, s. 577-579
-
Tidskriftsartikel (refereegranskat)abstract
- Background: We assessed response rates and compliance for a printed questionnaire and a Web questionnaire in a Swedish population-based study and explored the influence of adding personalized feedback to the Web questionnaire. Methods: We assigned 875 subjects to I of 3 groups: printed questionnaire, plain Web questionnaire, or Web questionnaire with personalized feedback. The questionnaire had 2 parts, first a general section and then a dietary section. Results: The response rate for the general section was 64% for the printed questionnaire, compared with 50% for the Web questionnaire with feedback. For the dietary questionnaire, the rates were reversed, resulting in a total response rate for the dietary questionnaire that did not differ between printed and web questionnaire with feedback. Conclusions: Interactivity in the Web questionnaire increased compliance in completion of the second section of the questionnaire. Web questionnaires can be useful for research purposes in settings in which Internet access is high.
|
|
| 49. |
- Carlsson, Sofia, et al.
(författare)
-
Body mass index and mortality : is the association explained by genetic factors?
- 2011
-
Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 22:1, s. 98-103
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Numerous studies have shown that higher body mass index (BMI) is associated with higher mortality. We investigated the extent to which this association might be explained by genetic factors. METHODS: We used data from the Swedish Twin Registry on twins born 1886-1958 who answered a questionnaire in 1969/1970 or 1972 (n = 44,258). Information on mortality from all-causes (n = 14,217), cardiovascular disease (CVD; n = 9009), and coronary heart disease (CHD; n = 3564) was obtained by linkage to the national Causes of Death Registry for the years 1972-2004. The association between BMI and mortality was studied without control for genetic factors in cohort analyses and with control for genetic factors in co-twin control analyses. RESULTS: In cohort analyses, there was a clear dose-response relationship between BMI and mortality. Hazard ratios per 1 unit increase in BMI in subjects with BMI ≥18.5 were 1.05 (95% confidence interval = 1.05-1.06) for all-cause mortality, 1.07 (1.07-1.09) for CVD mortality, and 1.09 (1.08-1.10) for CHD mortality. Similar results were seen in co-twin control analyses of dizygotic twins. However, within monozygotic twins, BMI was associated with death from CHD (OR = 1.06; 1.00-1.12), whereas the association with all-cause mortality (1.01, 0.98-1.04) and CVD mortality (1.02, 0.98-1.06) was weak. CONCLUSIONS: Our findings indicate that there is an association between high BMI and mortality from CHD that is not explained by genetic confounding. However, a large part of the association between BMI and other causes of death may be explained by genes rather than by a causal link between these factors.
|
|
| 50. |
|
|
