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Biomedical subjects

Marcel Zwahlen

Publications and source records attributed to Marcel Zwahlen.

At least 19 recordsLinked to original sources
PubMed2007

Surveillance systems for sexually transmitted diseases in Switzerland.

BACKGROUND: In Switzerland (population 7.4 million), 3 different systems contribute to surveillance for sexually transmitted infections. GOAL: The goal of this study was to compare time trends from surveillance systems for chlamydia, gonorrhea, and syphilis. STUDY DESIGN: We studied surveillance data (1997-2003) from laboratory reports in women and men, men attending dermatology clinics, and women attending gynecologists. RESULTS: Laboratory reports of episodes of Chlamydia trachomatis and Neisseria gonorrhoeae increased by 31% (from 2573 to 3449 cases) and 104% (from 259 to 528 cases), respectively. Over the same period, chlamydia reports from men attending dermatology clinics and women attending gynecologists did not change and dermatology clinic-based reports of gonorrhea in men increased only slightly. Syphilis reports from dermatology clinics increased by 127% (from 22 to 50 cases). CONCLUSIONS: Increases in laboratory reports of chlamydia and gonorrhea were not consistently detected in sentinel populations. Numbers of cases reported to all 3 systems were low. The performance of surveillance systems for sexually transmitted infections should be evaluated regularly.

Adolescent↗
PubMed2006

First trimester markers for pre-eclampsia: placental vs. non-placental protein serum levels.

BACKGROUND/AIM: Parallel investigation, in a matched case-control study, of the association of different first-trimester markers with the risk of subsequent pre-eclampsia (PE). METHOD: The levels of different first trimester serum markers and fetal nuchal translucency thickness were compared between 52 cases of PE and 104 control women by non-parametric two-group comparisons and by calculating matched odds ratios. RESULTS: In univariable analysis increased concentrations of inhibin A and activin A were associated with subsequent PE (p < 0.02). Multivariable conditional logistic regression models revealed an association between increased risk of PE and increased inhibin A and translucency thickness and respectively reduced pregnancy-associated plasma protein A (PAPP-A) and placental lactogen . However, these associations varied with the gestational age at sample collection. For blood samples taken in pregnancy weeks 12 and 13 only, increased levels of activin A, inhibin A and nuchal translucency thickness, and lower levels of placenta growth factor and PAPP-A were associated with an increased risk of PE. CONCLUSIONS: Members of the inhibin family and to some extent PAPP-A and placental growth factor are superior to other serum markers, and the predictive value of these depends on the gestational age at blood sampling. The availability of a single, early pregnancy 'miracle' serum marker for PE risk assessment seems unlikely in the near future.

Adult↗
PubMed2006

Influenza-attributable mortality among the elderly in Switzerland.

BACKGROUND: Influenza infections are considered responsible for a substantial burden of disease and mortality in the elderly, especially during winter time. However, death certificates indicating influenza as the cause of death might only partly reflect the mortality attributable to influenza. METHODS: We estimated influenza-attributable mortality for the Swiss resident population of age 60 and older from 1969 to 1999 by Poisson regression modelling of all cause and influenza mortality, and examined long-term trends by age and gender. In sensitivity analyses we additionally used data on official pneumonia deaths, as well as clinical diagnosis of influenza-associated illnesses from the Swiss Sentinel Network. RESULTS: For the 30 successive respiratory seasons (July of a given year to June of the next year) from 1969/70 to 1998/99 the estimated total number of influenza-attributable deaths in the Swiss population of 60+ was 24 800 (95% confidence interval: 21 000 to 28 600), about 2 times the official count of influenza deaths. Influenza-attributable mortality rate declined from 1969 to 1999, but the yearly number of influenza-attributable deaths nevertheless stabilised at around 600 to 700 in the ninety's due to aging of the population. The oldest-aged groups persistently showed the highest influenza mortality rate. Influenza-attributable mortality estimates were substantially higher when using the general practice influenza indicator (by 66%) or the combined cause-of-death category pneumonia and influenza (by 169%). CONCLUSIONS: Only counting official influenza deaths underestimated influenza-attributable mortality in Switzerland by a factor of two to three. Despite a gradual decline in age-specific influenza attributable mortality rates in the years 1969 to 1999, we estimated an average annual number of 830 deaths in the elderly Swiss resident population. The elderly remain the primary target group for influenza vaccination to reduce influenza-attributable mortality.

Age Distribution↗
PubMed2006

Educational inequalities in life expectancy in German speaking part of Switzerland 1990-1997: Swiss National Cohort.

STUDY OBJECTIVE: Switzerland belongs to the group of nations with the highest life expectancy. However, it is unclear to what extent life expectancy varies across socio-economic groups. We used data from a large longitudinal study to quantify differentials in life expectancy across educational groups for men and women of different ages. DESIGN: The Swiss National Cohort linked the records from the December 4th, 1990 census with death certificate data up to 1997, using a probabilistic record linkage method. The current analysis was restricted to Swiss nationals resident in the German speaking part of the country. Life expectancy was calculated for four educational categories ("compulsory schooling or less", "vocational training", "upper secondary education", "university education") by constructing abridged life tables for men and women aged 30 or older. RESULTS: The study was based on 3.06 million persons and 262,552 deaths recorded during 19.01 million person-years of follow up. The educational level was lower in women than in men. In most age groups vocational training was the dominant educational category. At ages 30, 50, 65 and 80 men with university education lived 7.1, 5.4, 3.5 and 1.6 years longer than their counterparts with compulsory education or less. In women the corresponding differences were 3.6, 3.1, 2.7 and 2.2 years. CONCLUSIONS: In Switzerland educational gradients in life expectancy are substantial, particularly among young and middle-aged men. Social policies and public health strategies should address this situation.

Adult↗
PubMed2006

Association between reported exposure to road traffic and respiratory symptoms in children: evidence of bias.

BACKGROUND: Many studies showing effects of traffic-related air pollution on health rely on self-reported exposure, which may be inaccurate. We estimated the association between self-reported exposure to road traffic and respiratory symptoms in preschool children, and investigated whether the effect could have been caused by reporting bias. METHODS: In a random sample of 8700 preschool children in Leicestershire, UK, exposure to road traffic and respiratory symptoms were assessed by a postal questionnaire (response rate 80%). The association between traffic exposure and respiratory outcomes was assessed using unconditional logistic regression and conditional regression models (matching by postcode). RESULTS: Prevalence odds ratios (95% confidence intervals) for self-reported road traffic exposure, comparing the categories 'moderate' and 'dense', respectively, with 'little or no' were for current wheezing: 1.26 (1.13-1.42) and 1.30 (1.09-1.55); chronic rhinitis: 1.18 (1.05-1.31) and 1.31 (1.11-1.56); night cough: 1.17 (1.04-1.32) and 1.36 (1.14-1.62); and bronchodilator use: 1.20 (1.04-1.38) and 1.18 (0.95-1.46). Matched analysis only comparing symptomatic and asymptomatic children living at the same postcode (thus exposed to similar road traffic) showed similar ORs, suggesting that parents of children with respiratory symptoms reported more road traffic than parents of asymptomatic children. CONCLUSIONS: Our study suggests that reporting bias could explain some or even all the association between reported exposure to road traffic and disease. Over-reporting of exposure by only 10% of parents of symptomatic children would be sufficient to produce the effect sizes shown in this study. Future research should be based only on objective measurements of traffic exposure.

Air Pollutants↗
PubMed2006

Helicobacter pylori infection and colorectal cancer risk: a meta-analysis.

BACKGROUND: Several studies suggested an association between Helicobacter pylori infection and colorectal carcinoma or adenoma risk. However, different authors reported quite varying estimates. We carried out a systematic review and meta-analysis of published studies investigating this association and paid special attention to the possibility of publication bias and sources of heterogeneity between studies. MATERIALS AND METHODS: An extensive literature search and cross-referencing were performed to identify all published studies. Summary estimates were obtained using random-effects models. The presence of possible publication bias was assessed using different statistical approaches. RESULTS: In a meta-analysis of the 11 identified human studies, published between 1991 and 2002, a summary odds ratio of 1.4 (95% CI, 1.1-1.8) was estimated for the association between H. pylori infection and colorectal cancer risk. The graphical funnel plot appeared asymmetrical, but the formal statistical evaluations did not provide strong evidence of publication bias. The proportion of variation of study results because of heterogeneity was small (36.5%). CONCLUSIONS: The results of our meta-analysis are consistent with a possible small increase in risk of colorectal cancer because of H. pylori infection. However, the possibility of some publication bias cannot be ruled out, although it could not be statistically confirmed. Larger, better designed and better controlled studies are needed to clarify the situation.

Adult↗
PubMed2005

Osteoporosis case finding in the general practice: phalangeal radiographic absorptiometry with and without risk factors for osteoporosis to select postmenopausal women eligible for lumbar spine and hip densitometry.

Mass screening for osteoporosis using DXA measurements at the spine and hip is presently not recommended by health authorities. Instead, risk factor questionnaires and peripheral bone measurements may facilitate the selection of women eligible for axial bone densitometry. The aim of this study was to validate a case finding strategy for postmenopausal women who would benefit most from subsequent DXA measurement by using phalangeal radiographic absorptiometry (RA) alone or in combination with risk factors in a general practice setting. The sensitivity and specificity of this strategy in detecting osteoporosis (T-score < or =2.5 SD at the spine and/or the hip) were compared with those of the current reimbursement criteria for DXA measurements in Switzerland. Four hundred and twenty-three postmenopausal women with one or more risk factors for osteoporosis were recruited by 90 primary care physicians who also performed the phalangeal RA measurements. All women underwent subsequent DXA measurement of the spine and the hip at the Osteoporosis Policlinic of the University Hospital of Berne. They were allocated to one of two groups depending on whether they matched with the Swiss reimbursement conditions for DXA measurement or not. Logistic regression models were used to predict the likelihood of osteoporosis versus "no osteoporosis" and to derive ROC curves for the various strategies. Differences in the areas under the ROC curves (AUC) were tested for significance. In women lacking reimbursement criteria, RA achieved a significantly larger AUC (0.81; 95% CI 0.72-0.89) than the risk factors associated with patients' age, height and weight (0.71; 95% C.I. 0.62-0.80). Furthermore, in this study, RA provided a better sensitivity and specificity in identifying women with underlying osteoporosis than the currently accepted criteria for reimbursement of DXA measurement. In the Swiss environment, RA is a valid case finding tool for patients with risk factors for osteoporosis, especially for those who do not qualify for DXA reimbursement.

Absorptiometry, Photon↗
PubMed2004

All cause mortality in the Swiss HIV Cohort Study from 1990 to 2001 in comparison with the Swiss population.

DESIGN: Mortality within the Swiss HIV Cohort Study for the years 1990-2001 was compared with the mortality of the general Swiss population. METHODS: Standardized mortality ratios (SMR) and life tables were calculated for strata defined by combinations of gender and HIV transmission group. The effect of dropouts was investigated with a sensitivity analysis and by analysing CD4 cell counts before dropout. RESULTS: During the study period 10 977 individuals had at least one cohort visit with a median observation time of 46 months. A total of 3630 patients died and 2290 dropped out. SMR decreased from 79.3 [95% confidence interval (CI), 77.2-81.5] before the introduction of highly active antiretroviral treatment (HAART) in 1996 to 15.3 (95% CI, 14.2-16.4) thereafter. For persons who acquired HIV infection by injecting drug use (IDUs), the SMR decreased from 98.2 (95% CI, 94.9-103.5) to 40.9 (95% CI, 37.0-44.8) after 1996; for all other HIV transmission groups the SMR decreased from 69.2 (95% CI, 66.9-71.6) to 9.4 (95% CI, 8.5-10.4). Thus, IDUs had significantly lower survival in comparison with other patient groups after 1996. Patients who had started HAART during the time period in which this treatment was available, had even lower SMRs. CONCLUSIONS: Although overall survival has improved considerably since the introduction of HAART, cohort life expectancy remains below that of the Swiss population. We noted, however, substantial differences in mortality among subgroups, and the results indicate that the additional risk related to injection drug use before 1996 had been masked by HIV-associated mortality.

Adolescent↗
PubMed2004

Mammography screening in Switzerland: limited evidence from limited data.

QUESTIONS UNDER STUDY: In Switzerland controversy exists on how to summarise the evidence on the efficacy and effectiveness, as well as adverse effects, of mammography screening, and breast cancer mortality trends are often discussed in the context of the impact of mammography. PRINCIPLES/METHODS: Single-study publications, meta-analyses, and reports by international expert groups on mammography screening are reviewed. Breast cancer mortality trends from 1970-2000 are reported and discussed in the context of the Swiss screening situation. RESULTS: In Switzerland breast cancer mortality rates for female Swiss nationals aged 50-79 years fell between 1990 and 2000 by some 25% in all language regions. The data from randomised studies in large populations in several countries with well organised mammography programmes prompt the conclusion that participation in organised screening programmes with rigorous quality standards reduces breast cancer mortality. The achievable long-term reduction in breast cancer mortality ranges from 5-20% in the target population provided that appropriate diagnostic investigation and treatment are available. To achieve this in Switzerland 830 to 3300 women need to be invited to screening for ten years to prevent one death from breast cancer. The risk-benefit profile of mammography screening is likely to be less favourable if mammographies are performed outside the context of organised screening programmes. In Switzerland we are now confronted with growing regional disparities in access to screening mammography which is under systematic quality control. CONCLUSIONS: The decrease in breast cancer mortality in Switzerland is most probably due to treatment developments and changes in cause-of-death coding. Public health measures in Switzerland should aim at regulating quality control for screening mammography, monitoring mammography use and improving the information on mammography available to women. For an evidence-based decision regarding health insurance coverage of screening mammography in 2007, large gaps need to be filled. The current coexistence of systematic screening programmes and opportunistic screening, with distinct regional differences, provides a unique opportunity for research into the merits and drawbacks of the two approaches.

Aged↗
PubMed2004

Insulin-like growth factor (IGF)-I, IGF binding protein-3, and cancer risk: systematic review and meta-regression analysis.

BACKGROUND: Insulin-like growth factor (IGF)-I and its main binding protein, IGFBP-3, modulate cell growth and survival, and are thought to be important in tumour development. Circulating concentrations of IGF-I might be associated with an increased risk of cancer, whereas IGFBP-3 concentrations could be associated with a decreased cancer risk. METHODS: We did a systematic review and meta-regression analysis of case-control studies, including studies nested in cohorts, of the association between concentrations of IGF-I and IGFBP-3 and prostate, colorectal, premenopausal and postmenopausal breast, and lung cancer. Study-specific dose-response slopes were obtained by relating the natural log of odds ratios for different exposure levels to blood concentrations normalised to a percentile scale. FINDINGS: We identified 21 eligible studies (26 datasets), which included 3609 cases and 7137 controls. High concentrations of IGF-I were associated with an increased risk of prostate cancer (odds ratio comparing 75th with 25th percentile 1.49, 95% CI 1.14-1.95) and premenopausal breast cancer (1.65, 1.26-2.08) and high concentrations of IGFBP-3 were associated with increased risk of premenopausal breast cancer (1.51, 1.01-2.27). Associations were larger in assessments of plasma samples than in serum samples, and in standard case-control studies compared with nested studies. INTERPRETATION: Circulating concentrations of IGF-I and IGFBP-3 are associated with an increased risk of common cancers, but associations are modest and vary between sites. Although laboratory methods need to be standardised, these epidemiological observations could have major implications for assessment of risk and prevention of cancer.

Breast Neoplasms↗
PubMed2004

Clinical efficacy of antiretroviral combination therapy based on protease inhibitors or non-nucleoside analogue reverse transcriptase inhibitors: indirect comparison of controlled trials.

OBJECTIVE: To compare the clinical efficacy of triple antiretroviral regimens based on protease inhibitors and non-nucleoside analogue reverse transcriptase inhibitors (NNRTIs) in adults positive for antibodies to HIV-1. DESIGN: Systematic review and meta-analysis using indirect comparisons of clinical trials comparing three drug regimens based on two nucleoside reverse transcriptase inhibitors (NRTIs) and either a protease inhibitor or an NNRTI with two drug regimens (two NRTIs). Participants had no previous exposure to protease inhibitors or NNRTIs. DATA SOURCES: Medline, the Cochrane controlled trials register, Aidstrials, Aidsdrugs, conference proceedings, and trial registers. MAIN OUTCOME MEASURE: Progression to AIDS or death. RESULTS: 14 trials, totalling 6785 patients, were identified. Most patients had been exposed to an NRTI and had advanced immunodeficiency at baseline; 1096 progressed to AIDS or died. Seven trials assessed protease inhibitors based triple regimens and seven assessed NNRTI based triple regimens (nevirapine or delavirdine). Triple therapy was more effective than dual therapy. The effect was pronounced for protease inhibitor based regimens (odds ratio 0.49, 95% confidence interval 0.41 to 0.58) but non-significant for NNRTI based regimens (0.90, 0.71 to 1.15). Indirect comparison of the two regimens gave an odds ratio of 0.54 (0.49 to 0.73) in favour of protease inhibitor based treatments. Increases in CD4 cell counts were smaller and suppression of viral replication less with NNRTI based regimens. CONCLUSIONS: Indirect evidence shows that protease inhibitor based triple regimens are superior to regimens based on the NNRTIs nevirapine and delavirdine in patients with advanced immunodeficiency who have been exposed to NRTIs. Large trials with clinical end points are required.

Acquired Immunodeficiency Syndrome↗
PubMed2004

The association of biomass fuel combustion on pulmonary function tests in the adult population of Mid-Anatolia.

OBJECTIVES: To assess the association of biomass as domestic energy source on respiratory function in rural areas of Mid-Anatolia in Turkey where biomass use is frequent. METHODS: In a cross-sectional study, pulmonary functions measurements of 112 cow-dung users and 153 modern energy source users, all non-smokers, were assessed and compared. Several sociodemographic factors were assessed by questionnaire, and ventilatory function measurements included forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio and the flow between the first 25 and 75 of forced expiratory flow (FEF(25-75)), and were compared, deploying univariate and multivariate methods, between the two groups. RESULTS: The individuals in the biomass exposed and unexposed group were similar regarding demographic characteristics: 67.0% were female (exposed) vs 60.1% (unexposed) with an age range of 17 to 64 (exposed) and 18 to 70 years (unexposed), and with 36% of biomass users having had pulmonary tract infections (20% in non-users). For all pulmonary function test parameters FEV1, FVC, FEV1/FVC, and FEF(25-75) a highly significant (p < 0.0001) reduction was observed in biomass users. A 12.4% (95% confidence interval: 7.0% to 17.7%) reduction in forced vital capacity was observed in multivariate linear regression. CONCLUSIONS: It is well known that biomass combustion is a relevant public health problem. The substantial differences in pulmonary functions associated with biomass use as an energy source observed in this cross-sectional study in non-smokers support that also in rural Turkey measures may be in need to reduce this public health problem.

Adult↗
PubMed2004

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years.

OBJECTIVES: The objective of this systematic review was to assess the 5- and 10-year survival of implant supported fixed partial dentures (FPDs) and to describe the incidence of biological and technical complications. METHODS: An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on FPDs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by two reviewers. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions. RESULTS: The search provided 3844 titles and 560 abstracts. Full-text analysis was performed for 176 articles resulting in 21 studies that met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants in implant-supported FPDs of 95.4% (95 percent confidence interval (95% CI): 93.9-96.5%) after 5 and 92.8% (95% CI: 90-94.8%) after 10 years. The survival rate of FPDs supported by implants was 95% (95% CI: 92.2-96.8%) after 5 and 86.7% (95% CI: 82.8-89.8%) after 10 years of function. Only 61.3% (95% CI: 55.3-66.8%) of the patients were free of any complications after 5 years. Peri-implantitis and soft tissue complications occurred in 8.6% (95% CI: 5.1-14.1%) of FPDs after 5 years. Technical complications included implant fractures, connection-related and suprastructure-related complications. The cumulative incidence of implant fractures after 5 years was 0.4% (95% CI: 0.1-1.2%). After 5 years, the cumulative incidence of connection-related complications (screw loosening or fracture) was 7.3% and 14% for suprastructure-related complications (veneer and framework fracture). CONCLUSION: Despite a high survival of FPDs, biological and technical complications are frequent. This, in turn, means that substantial amounts of chair time have to be accepted by the clinician following the incorporation of implant-supported FPDs. More studies with follow-up times of 10 and more years are needed as only few studies have described the long-term outcomes.

Algorithms↗