Adrian Spoerri

Decreasing mortality and changing patterns of causes of death in the Swiss HIV Cohort Study

Mortality among HIV‐infected persons is decreasing, and causes of death are changing. Classification of deaths is hampered because of low autopsy rates, frequent deaths outside of hospitals, and shortcomings of International Statistical Classification of Diseases and Related Health Problems (ICD‐10) coding.

Cohort Profile: The Swiss National Cohort—a longitudinal study of 6.8 million people

For many years research on socio-economic inequalities in health in Switzerland was based on crosssectional data. Cross-sectional studies are problematic for several reasons. For example, results may be affected by numerator/denominator bias. Furthermore, occupational information from death certificates was used to describe the socio-economic position of individuals. However, this meant that those who do not work, older men and a substantial proportion of women, had to be excluded. Decennial censuses, conducted at the beginning of December every 10 years, have been done in Switzerland since 1850 (exceptions were 1890 and 1940, which were replaced by a census in 1888 and 1941, respectively). Deaths and causes of death have been registered since 1876, with data stored electronically since 1969. Death registration is anonymous. However, the date of death and birth are available, as well as gender, marital status, place of residence, date of birth of spouse and other variables. The 1990 census for the first time included the exact date of birth, which opened the possibility of linking census and mortality data. Based on the promising results of a pilot study that was done for one Canton at University of Zurich, the project was extended to cover the whole of Switzerland, linking the 1990 census with mortality records up to the end of 1997. The results indicated that linkage was less successful for foreign nationals and young adults, and led to the inclusion of additional data sources, including data on immigrants and emigrants and, importantly, the 2000 census. In 2005, an application by all five University Institutes of Social and Preventive Medicine (ISPMs) to obtain long-term funding for a Swiss National Cohort study (SNC) was successful within the framework of a Swiss National Science Foundation initiative to support longitudinal studies. Approval was obtained from the Ethics Committees of the Cantons of Zurich and Bern and a data centre was established at ISPM Bern.

Aircraft noise, air pollution, and mortality from myocardial infarction

Objective: Myocardial infarction has been associated with both transportation noise and air pollution. We examined residential exposure to aircraft noise and mortality from myocardial infarction, taking air pollution into account. Methods: We analyzed the Swiss National Cohort, which includes geocoded information on residence. Exposure to aircraft noise and air pollution was determined based on geospatial noise and air-pollution (PM10) models and distance to major roads. We used Cox proportional hazard models, with age as the timescale. We compared the risk of death across categories of A-weighted sound pressure levels (dB(A)) and by duration of living in exposed corridors, adjusting for PM10 levels, distance to major roads, sex, education, and socioeconomic position of the municipality. Results: We analyzed 4.6 million persons older than 30 years who were followed from near the end of 2000 through December 2005, including 15,532 deaths from myocardial infarction (ICD-10 codes I 21, I 22). Mortality increased with increasing level and duration of aircraft noise. The adjusted hazard ratio comparing ≥60 dB(A) with <45 dB(A) was 1.3 (95% confidence interval = 0.96-1.7) overall, and 1.5 (1.0-2.2) in persons who had lived at the same place for at least 15 years. None of the other endpoints (mortality from all causes, all circulatory disease, cerebrovascular disease, stroke, and lung cancer) was associated with aircraft noise. Conclusion: Aircraft noise was associated with mortality from myocardial infarction, with a dose-response relationship for level and duration of exposure. The association does not appear to be explained by exposure to particulate matter air pollution, education, or socioeconomic status of the municipality.

Residence Near Power Lines and Mortality From Neurodegenerative Diseases: Longitudinal Study of the Swiss Population

The relation between residential magnetic field exposure from power lines and mortality from neurodegenerative conditions was analyzed among 4.7 million persons of the Swiss National Cohort (linking mortality and census data), covering the period 2000-2005. Cox proportional hazard models were used to analyze the relation of living in the proximity of 220-380 kV power lines and the risk of death from neurodegenerative diseases, with adjustment for a range of potential confounders. Overall, the adjusted hazard ratio for Alzheimers disease in persons living within 50 m of a 220-380 kV power line was 1.24 (95% confidence interval (CI): 0.80, 1.92) compared with persons who lived at a distance of 600 m or more. There was a dose-response relation with respect to years of residence in the immediate vicinity of power lines and Alzheimers disease: Persons living at least 5 years within 50 m had an adjusted hazard ratio of 1.51 (95% CI: 0.91, 2.51), increasing to 1.78 (95% CI: 1.07, 2.96) with at least 10 years and to 2.00 (95% CI: 1.21, 3.33) with at least 15 years. The pattern was similar for senile dementia. There was little evidence for an increased risk of amyotrophic lateral sclerosis, Parkinsons disease, or multiple sclerosis.

A Swiss neighbourhood index of socioeconomic position: development and association with mortality

Background Area-based measures of socioeconomic position (SEP) suitable for epidemiological research are lacking in Switzerland. The authors developed the Swiss neighbourhood index of SEP (Swiss-SEP). Methods Neighbourhoods of 50 households with overlapping boundaries were defined using Census 2000 and road network data. Median rent per square metre, proportion households headed by a person with primary education or less, proportion headed by a person in manual or unskilled occupation and the mean number of persons per room were analysed in principle component analysis. The authors compared the index with independent income data and examined associations with mortality from 2001 to 2008. Results 1.27 million overlapping neighbourhoods were defined. Education, occupation and housing variables had loadings of 0.578, 0.570 and 0.362, respectively, and median rent had a loading of −0.459. Mean yearly equivalised income of households increased from SFr42 000 to SFr72 000 between deciles of neighbourhoods with lowest and highest SEP. Comparing deciles of neighbourhoods with lowest to highest SEP, the age- and sex-adjusted HR was 1.38 (95% CI 1.36 to 1.41) for all-cause mortality, 1.83 (95% CI 1.71 to 1.95) for lung cancer, 1.48 (95% CI 1.44 to 1.51) for cardiovascular diseases, 2.42 (95% CI 1.94 to 3.01) for traffic accidents, 0.93 (95% CI 0.85 to 1.02) for breast cancer and 0.86 (95% CI 0.78 to 0.95) for suicide. Conclusions Developed using a novel approach to define neighbourhoods, the Swiss-SEP index was strongly associated with household income and some causes of death. It will be useful for clinical- and population-based studies, where individual-level socioeconomic data are often missing, and to investigate the effects on health of the socioeconomic characteristics of a place.

Retention in care during the first 3 years of antiretroviral therapy for women in Malawi's option B+ programme: an observational cohort study

BACKGROUND Studies of Malawis option B+ programme for HIV-positive pregnant and breastfeeding women have reported high loss to follow-up during pregnancy and at the start of antiretroviral therapy (ART), but few data exist about retention during breastfeeding and after weaning. We examined loss to follow-up and retention in care in patients in the option B+ programme during their first 3 years on ART. METHODS We analysed two data sources: aggregated facility-level data about patients in option B+ who started ART between Oct 1, 2011, and June 30, 2012, at 546 health facilities; and patient-level data from 20 large facilities with electronic medical record system for HIV-positive women who started ART between Sept 1, 2011, and Dec 31, 2013, under option B+ or because they had WHO clinical stages 3 or 4 disease or had CD4 counts of less than 350 cells per μL. We used facility-level data to calculate representative estimates of retention and loss to follow-up. We used patient-level data to study temporal trends in retention, timing of loss to follow-up, and predictors of no follow-up and loss to follow-up. We defined patients who were more than 60 days late for their first follow-up visit as having no follow-up and patients who were more than 60 days late for a subsequent visit as being lost to follow-up. We calculated proportions and cumulative probabilities of patients who had died, stopped ART, had no follow-up, were lost to follow-up, or were retained alive on ART for 36 months. We calculated odds ratios and hazard ratios to examine predictors of no follow-up and loss to follow-up. FINDINGS Analysis of facility-level data about patients in option B+ who had not transferred to a different facility showed retention in care to be 76·8% (20 475 of 26,658 patients) after 12 months, 70·8% (18,306 of 25,849 patients) after 24 months, and 69·7% (17,787 of 25,535 patients) after 36 months. Patient-level data included 29,145 patients. 14,630 (50·2%) began treatment under option B+. Patients in option B+ had a higher risk of having no follow-up and, for the first 2 years of ART, higher risk of loss to follow-up than did patients who started ART because they had CD4 counts less than 350 cells per μL or WHO clinical stage 3 or 4 disease. Risk of loss to follow-up during the third year was low and similar for patients retained for 2 years. Retention rates did not change as the option B+ programme matured. INTERPRETATION Our data suggest that pregnant and breastfeeding women who start ART immediately after they are diagnosed with HIV can be retained on ART through the option B+ programme, even after many have stopped breastfeeding. Interventions might be needed to improve retention in the first year on ART in option B+. FUNDING Bill & Melinda Gates Foundation, Partnerships for Enhanced Engagement in Research Health, and National Institute of Allergy and Infectious Diseases.

Suicide in HIV-Infected Individuals and the General Population in Switzerland, 1988–2008

OBJECTIVE High rates of suicide have been described in HIV-infected patients, but it is unclear to what extent the introduction of highly active antiretroviral therapy (HAART) has affected suicide rates. The authors examined time trends and predictors of suicide in the pre-HAART (1988-1995) and HAART (1996-2008) eras in HIV-infected patients and the general population in Switzerland. METHOD The authors analyzed data from the Swiss HIV Cohort Study and the Swiss National Cohort, a longitudinal study of mortality in the Swiss general population. The authors calculated standardized mortality ratios comparing HIV-infected patients with the general population and used Poisson regression to identify risk factors for suicide. RESULTS From 1988 to 2008, 15,275 patients were followed in the Swiss HIV Cohort Study for a median duration of 4.7 years. Of these, 150 died by suicide (rate 158.4 per 100,000 person-years). In men, standardized mortality ratios declined from 13.7 (95% CI=11.0-17.0) in the pre-HAART era to 3.5 (95% CI=2.5-4.8) in the late HAART era. In women, ratios declined from 11.6 (95% CI=6.4-20.9) to 5.7 (95% CI=3.2-10.3). In both periods, suicide rates tended to be higher in older patients, in men, in injection drug users, and in patients with advanced clinical stage of HIV illness. An increase in CD4 cell counts was associated with a reduced risk of suicide. CONCLUSIONS Suicide rates decreased significantly with the introduction of HAART, but they remain above the rate observed in the general population, and risk factors for suicide remain similar. HIV-infected patients remain an important target group for suicide prevention.

Impact of unlinked deaths and coding changes on mortality trends in the Swiss National Cohort

BackgroundResults of epidemiological studies linking census with mortality records may be affected by unlinked deaths and changes in cause of death classification. We examined these issues in the Swiss National Cohort (SNC).MethodsThe SNC is a longitudinal study of the entire Swiss population, based on the 1990 (6.8 million persons) and 2000 (7.3 million persons) censuses. Among 1,053,393 deaths recorded 1991–2007 5.4% could not be linked using stringent probabilistic linkage. We included the unlinked deaths using pragmatic linkages and compared mortality rates for selected causes with official mortality rates. We also examined the impact of the 1995 change in cause of death coding from version 8 (with some additional rules) to version 10 of the International Classification of Diseases (ICD), using Poisson regression models with restricted cubic splines. Finally, we compared results from Cox models including and excluding unlinked deaths of the association of education, marital status, and nationality with selected causes of death.ResultsSNC mortality rates underestimated all cause mortality by 9.6% (range 2.4% - 17.9%) in the 85+ population. Underestimation was less pronounced in years nearer the censuses and in the 75–84 age group. After including 99.7% of unlinked deaths, annual all cause SNC mortality rates were reflecting official rates (relative difference between −1.4% and +1.8%). In the 85+ population the rates for prostate and breast cancer dropped, by 16% and 21% respectively, between 1994 and 1995 coincident with the change in cause of death coding policy. For suicide in males almost no change was observed. Hazard ratios were only negligibly affected by including the unlinked deaths. A sudden decrease in breast (21% less, 95% confidence interval: 12% - 28%) and prostate (16% less, 95% confidence interval: 7% - 23%) cancer mortality rates in the 85+ population coincided with the 1995 change in cause of death coding policy.ConclusionsUnlinked deaths bias analyses of absolute mortality rates downwards but have little effect on relative mortality. To describe time trends of cause-specific mortality in the SNC, accounting for the unlinked deaths and for the possible effect of change in death certificate coding was necessary.

The Swiss National Cohort: a unique database for national and international researchers

Longitudinal studies, also known as cohort studies, collect data on a large number of individuals at different points in time. These studies allow tracking changes of health status, presence of diseases and risk factors in human populations. Many longitudinal studies of large parts or the whole resident population have been established in the United Kingdom and in Nordic countries where population registries and unique person identifiers facilitate the linkage of existing databases. In contrast, information on the health of the Swiss population is limited. The Swiss Health Surveys are cross-sectional and the few existing prospective studies are not representative for the population at large. Death certificate data have been used to describe differentials in mortality by occupation (Minder et al. 1986) but analyses used proportionate mortality and excluded older men and many women. The Swiss National Cohort (SNC) was set up to improve this situation by providing a national data platform and developing a multi-faceted research programme. Following several pilot projects, the SNC has been funded by the Swiss National Science Foundation since 2006. Anatomy of the SNC

Religion and assisted and non-assisted suicide in Switzerland: National Cohort Study

BACKGROUND In the 19th century, eminent French sociologist Emile Durkheim found suicide rates to be higher in the Protestant compared with the Catholic cantons of Switzerland. We examined religious affiliation and suicide in modern Switzerland, where assisted suicide is legal. METHODS The 2000 census records of 1,722,456 (46.0%) Catholics, 1,565,452 (41.8%) Protestants and 454,397 (12.2%) individuals with no affiliation were linked to mortality records up to December 2005. The association between religious affiliation and suicide, with the Protestant faith serving as the reference category, was examined in Cox regression models. Hazard ratios (HRs) with 95% confidence intervals (CIs) were adjusted for age, marital status, education, type of household, language and degree of urbanization. RESULTS Suicide rates per 100,000 inhabitants were 19.7 in Catholics (1664 suicides), 28.5 in Protestants (2158 suicides) and 39.0 in those with no affiliation (882 suicides). Associations with religion were modified by age and gender (P < 0.0001). Compared with Protestant men aged 35-64 years, HRs (95% CI) for all suicides were 0.80 (0.73-0.88) in Catholic men and 1.09 (0.98-1.22) in men with no affiliation; and 0.60 (0.53-0.67) and 1.96 (1.69-2.27), respectively, in men aged 65-94 years. Corresponding HRs in women aged 35-64 years were 0.90 (0.80-1.03) and 1.46 (1.25-1.72); and 0.67 (0.59-0.77) and 2.63 (2.22-3.12) in women aged 65-94 years. The association was strongest for suicides by poisoning in the 65-94-year-old age group, the majority of which was assisted: HRs were 0.45 (0.35-0.59) for Catholic men and 3.01 (2.37-3.82) for men with no affiliation; 0.44 (0.36-0.55) for Catholic women and 3.14 (2.51-3.94) for women with no affiliation. CONCLUSIONS In Switzerland, the protective effect of a religious affiliation appears to be stronger in Catholics than in Protestants, stronger in older than in younger people, stronger in women than in men, and particularly strong for assisted suicides.