Rudolf Mak

Occupational stress and incidence of sick leave in the Belgian workforce: the Belstress study

Context: Sick leave is a major problem in public health. The Karasek demands/control/social support/strain (JDCS) model has been largely used to predict a wide range of health outcomes and to a lesser extent sickness absence. Study objective: The aim of the study was to test the predictive power of the JDCS model in relation with one year incidence of sick leave in a large cohort of workers. Design and setting: Cohort study conducted between 1994 and 1998 in 25 companies across Belgium. Participants: A total of 20 463 workers aged 35 to 59 years were followed up for sick leave during one year after the baseline survey. Outcomes: The outcomes were a high sick leave incidence, short spells (⩾7 days), long spells (⩾28 days), and repetitive spells of sickness absence (⩾3 spells/year). Main results: Independently from baseline confounding variables, a significant association between high strained jobs with low social support and repetitive spells of sickness absence was observed in both sexes with odds ratios of 1.32 (99% CI, 1.04 to 1.68) in men and 1.61 (99% CI, 1.13 to 2.33) in women. In men, high strained jobs with low social support was also significantly associated with high sick leave incidence, and short spells of sick leave with odds ratios of 1.38 (99% CI, 1.16 to 1.64) and 1.22 (99% CI, 1.05 to 1.44) respectively. Conclusions: Perceived high strain at work especially combined with low social support is predictive of sick leave in both sexes of a large cohort of the Belgian workforce.

Alcohol and risky sex: In search of an elusive connection

Since the publication of the 1986 article by Stall, McKusick, Wiley, Coates and Ostrow, the conclusion that drinking alcohol prior to or during erotic encounters increases the probability of engaging in high-risk sexual behavior has been widely accepted, despite some contradictory findings from research on this hypothesis. This paper presents the results of tests of the alcohol/risky-sex hypothesis in a cohort of gay men in Flanders, Belgium. Failing to find evidence to support the hypothesis of a general effect of alcohol on sexual risk taking, we argue that previous conclusions on this matter must be viewed with extreme caution, especially in light of the implications that this failure to replicate has for AIDS prevention programs. Cultural, social, and methodological factors that could account for this failure to replicate are discussed in the context of a review of the literature on this hypothesis.

Prevalence of hepatitis A, B and C in the Flemish population

Viral hepatitis is a serious health problem throughout the world. No recent prevalence data on hepatitis A, B and C were available for the population in Flanders, Belgium. For this reason, a sero-epidemiological study was undertaken in 1993–1994 in a sample of the general population. The purpose of this study was to obtain a clear picture of the prevalence of hepatitis A, B and C. Between April 1993 and February 1994, 4,058 blood samples were drawn and collected in 10 hospitals in Flanders. The study group was representative for the Flemish population. For hepatitis A a seroprevalence of 55.1% was found. In the non-Belgian residents the HAV prevalence was significantly higher than in Belgians (62% versus 52%; χ2 = 8.05; p = 0.005). For hepatitis B, 9.9% of the study group showed serological evidence of hepatitis B markers: 6.9% of the participants was positive for anti-HBs/anti-HBc, 0.7% appeared to be HBsAg positive and 3.5% was solely anti-HBs positive. The prevalence of HBV markers in Belgians was 6.9%, significantly lower compared to the 13.4% among non-Belgians (χ2 = 14.05; p = 0.00018). 4055 serum samples were analysed for hepatitis C serology by second generation anti-HCV tests. Anti-HCV was detected in 0.87% of the serum samples. No statistically significant difference was found in HCV prevalence between Belgians and non-Belgians. Results of this study should help policy makers in their decisions on the most appropriate hepatitis A and B vaccination strategy and on the most effective prevention strategy for hepatitis C.

Obesity, body fat distribution and incidence of sick leave in the Belgian workforce: the Belstress study

OBJECTIVES: In many studies, obesity has been associated with morbidity or mortality, but only a few have studied the relation between obesity and sick leave. Our aim is to analyse the independent effects of both adiposity and body fat distribution in relation to the 1-y incidence of sick leave in a large cohort of male and female workers covering a variety of occupations, taking into account a wide range of socio-demographic, behavioural and bioclinical variables.DESIGN AND SETTING: The baseline survey of the Belstress study was conducted in 25 companies across Belgium between 1994 and 1998. A cohort of 20 463 workers (15 557 males and 4906 females) aged 35–59 y was followed for absenteeism during 1 y. The 75th percentile of the distribution of the total annual sickness days was used as a cutoff to classify the workers with a high 1-y incidence rate of sick leave. The relation between sick leave and both obesity and body fat distribution assessed by the body mass index (BMI) and the waist circumference, respectively, was analysed by multivariate logistic regression models.RESULTS: Using a backward procedure based on the likelihood ratio, we found central abdominal fatness to be an independent predictor of sick leave in both genders (high sick-leave incidence and long spells), but not BMI. In men, the odds ratios was 1.31 (99% CI 1.12–1.52, P<0.0001) and in women it ranged from 1.32 (99% CI 1.03–1.70, P=0.005) to 1.47 (99% CI 1.14–1.90, P<0.0001). Two baseline covariables, respiratory problems and perceived health, are confounders or mediators.CONCLUSIONS: In this study, body fat distribution was associated with a high annual sick-leave incidence and long spells of sickness absence. If this link is reversible, employers may benefit from programs aiming at the prevention and treatment of central obesity.

Discriminative value of serum amyloid A and other acute-phase proteins for coronary heart disease

We studied the value of serum amyloid A (SAA), a first-class acute-phase protein, as a marker for coronary heart disease (CHD) in a middle-aged male population. In a working population of 16307 men (age, 35-59 years), 446 cases had a history of CHD or prominent Q:QS waves on electrocardiogram. For each case, two matched controls were investigated. SAA, measured by immunonephelometry, was correlated with other acute-phase proteins, cardiovascular risk factors, and infectious serology markers. SAA concentrations were significantly higher in the cases than in controls (P<0.05) and correlated with serum C-reactive protein (CRP) (r=0.61), plasma fibrinogen (r=0.39), serum haptoglobin (r=0.26), and body mass index (r=0.13) (P<0.001). Serum CRP is a better marker for CHD than SAA, which showed discriminative power only in a univariate model comparing highest versus lowest tertile (odds ratio, 1.39; 95% confidence interval, 1.03-1.87). Neither SAA nor other acute-phase proteins correlated with Chlamydia pneumoniae immunoglobulin (Ig)G, Helicobacter pylori IgG and IgA, and cytomegalovirus IgG. In conclusion, although SAA has a discriminative value for CHD, serum CRP is to be preferred as a first-class acute-phase reactant for detection of the disease.

Importance of Methodology in Determination of Chlamydia pneumoniae Seropositivity in Healthy Subjects and in Patients with Coronary Atherosclerosis

ABSTRACT Enzyme immunoassays (EIAs) for the detection of Chlamydia pneumoniae antibodies were compared to the microimmunofluorescence (MIF) test, the reference method. Furthermore, we assessed the hypothesis that a possible relationship between Chlamydia pneumoniae immunoglobulin G (IgG) antibodies and coronary artery disease is dependent on the type of EIA. Sera from 112 healthy men (mean age, 50.1 years) were tested for antibodies against Chlamydia pneumoniae by five commercial test kits: Focus Chlamydia MIF IgG test, Labsystems Chlamydia pneumoniae IgG EIA (LS EIA), R-Biopharm Elegance Chlamydia pneumoniae IgG EIA (RB EIA), Medac Chlamydia pneumoniae IgG sandwich enzyme-linked immunosorbent assay ELISA (MCp sELISA) and Medac Chlamydia IgG recombinant enzyme-linked immunosorbent assay ELISA (MC rELISA). Sera from 106 consecutive male patients (mean age, 63.6 years) undergoing diagnostic coronary angiography were also examined using the Focus MIF, LS EIA, MCp sELISA, and MC rELISA techniques. The agreement between LS EIA (65 to 83% [controls-patients]) or MC rELISA (49 to 61%) and Focus MIF (78 to 83%) was average to fair (κ = 0.597 and 0.234, respectively). MCp sELISA and RB EIA showed good agreement with MIF (κ = 0.686 and 0.665, respectively), with 80 to 89 and 79% of individuals reacting positively. A significant difference in seroprevalence between patients and healthy subjects was observed with the LS EIA, while seropositivities in the two study groups appeared equal when the Focus MIF assay was applied. The MC rELISA and MCp sELISA gave statistically significant differences in antibody seroprevalence in patients with two-vessel disease or when the patient group combined individuals with a two- or a three-vessel disease, respectively. The concordance between MIF and other commonly used serological assays for C. pneumoniae IgG antibody detection is good to fair. The choice of serological assay has important implications for C. pneumoniae antibody seroprevalence, as well as for the relationship between C. pneumoniae seropositivity and coronary artery disease.

Cervical smears and human papillomavirus typing in sex workers.

Objectives: Sex workers are at increased risk for sexually transmitted infections (STI), human papillomavirus (HPV) and hence cervical cancer. In Belgium screening for cervical cancer starts at the age of 25, and is at 3 yearly intervals. The aim of this study is to assess risks for abnormal cervical smears and HPV in sex workers and decide whether the current screening policy is sufficient for them. Methods: In an outreach programme for sex workers results of 653 smears sampled between 1992 and 2001 were analysed, and compared to a control group matched for age from the general population in 2001. Separately, 99 consecutive samples were typed for HPV and compared to an equal control group, matched for age. Smears and typing were performed according to current techniques. Results: In the sex worker group 2.6% were diagnosed with atypical glandular cells of undetermined significance (AGUS)/atypical squamous cells of undetermined significance (ASCUS), 15.6% with low grade squamous intraepithelial lesion (LSIL), and 2.9% with high grade squamous intraepithelial lesion (HSIL), and in the control group results were 1.4%, 2.9% (p<0.001) and 0.6% (p<0.001) respectively. When considering only those under 25 years, 24.4% should have further follow up. Of the sex workers, 77.4% were positive for one or more types of HPV (55.9% for high risk HPV), in comparison with 27.6% of the control group (14.3% for high risk HPV) (p<0.001). In high risk HPV samples more LSIL and HSIL were found. Conclusion: Abnormal smears and high risk HPV were significantly more prevalent in sex workers than in controls. Current screening policy would miss many sex workers with an abnormal smear who should be referred for further follow up. It is proposed to screen sex workers when they enter prostitution regardless of their age.

Parameters of inflammation and infection in a community based case-control study of coronary heart disease

BACKGROUND increased levels of systemic inflammatory markers appear to be related to coronary heart disease (CHD) both in asymptomatic individuals and in subjects with established CHD. Whether these associations are related to confounding coronary risk factors or are explicable through chronic infectious conditions is not clear. OBJECTIVES (1) to determine whether subjects with stable CHD differ from normal controls in inflammatory markers (CRP, SAA and fibrinogen) and/or in serostatus of four infectious agents (Helicobacter pylori, Chlamydia pneumoniae, CMV and EBV), independent of classical coronary risk factors. (2) To determine whether these inflammatory markers are related to the serostatus against these four infectious agents either in patients with CHD or in normal subjects. METHODS in a large epidemiologic survey, 446 out of 16307 men at work, aged 35-59 years, had antecedents of myocardial infarction, CABG or PTCA or had prominent Q/QS waves on their resting ECG. They were compared with double the number (n=892) of men, matched for age, educational level and industry. Inflammatory biomarkers (CRP, fibrinogen and SAA) and antibodies against H. pylori, C. pneumoniae, CMV and EBV were measured, besides classical coronary risk factors. RESULTS in univariate analyses, cases had higher CRP, fibrinogen and SAA levels than controls, but no differences were observed in serumantibody levels to any of the infectious agents. Markers of previous infections were not related to inflammatory biomarkers. In multivariate analyses CRP was significantly different between cases and controls independent of differences in other coronary risk factors and in the use of lipid lowering drugs and antiplatelet aggregants. CONCLUSIONS in men at work with CHD, CRP levels are significantly different from controls, independent of known risk factors. No association was found between inflammatory biomarkers and positive serostatus against four infectious agents, neither in the patients nor in the healthy controls.

Hepatitis B vaccination for sex workers: do outreach programmes perform better?

Objectives: To assess to what extent hepatitis B vaccination of sex workers in Ghent, Belgium, is successful within the context of the existing health services and to compare this with alternative approaches such as outreach programmes; to compare two hepatitis B vaccination schemes in the outreach programme for sex workers. Methods: Testing all first contacts (n = 1096) in the outreach programme for hepatitis B virus (HBV) markers assessed success of hepatitis B vaccination in routine services. The performance of the outreach service was measured by counting the number of sex workers who started hepatitis B vaccination in the programme. The hepatitis B vaccination schemes were assessed by analysing the number of people completing the vaccination. Results: Naturally acquired HBV was found in 11.9% of 1096 sex workers (0.6% HBsAg), and 7% were vaccinated in existing services. In contrast, hepatitis B vaccination using outreach methodology was able to achieve higher vaccination rates: among non-immune sex workers 82.8% received the first dose of vaccine, and 71.5% the second. If given 1 month later, 67.9% received the third dose, in contrast with 47.9%, when given 6 months later. Conclusions: Existing services are not successful in vaccinating sex workers for HBV, in contrast with specifically targeted outreach services. Shorter intervals between vaccine doses gave better compliance.

Coming out and AIDS-related high-risk sexual behavior.

How the withdrawal of social support associated with the coming out of gay men influences AIDS-related sexual risk-taking among Flemish (Belgian) gay men is analyzed. Recruited via key persons, the 379 gay men in this nonclinical cohort completed a lengthy, computerized questionnaire dealing with diverse aspects of gay life and culture. Independent variables include demographic characteristics, AIDS knowledge, coming-out histories, six social support dimensions, and personal resources. The dependent variables were insertive and receptive anal intercourse with and without a condom. Stepwise regression explained, respectively, 41.2, 38.4, 18.4, and 14.2% of the variance. Absence of appraisal (the view that others approve of the way one does things or feels about things) led to higher frequencies of insertive anal sex (both with and without a condom). The experience of emotional conflict lowered the use of condoms by the insertive partner in anal intercourse. Disapproval by significant others of being gay also led to higher levels of receptive anal intercourse without a condom. Subjects with a high belief in mastery had higher frequencies of risk-taking, suggesting that the combination of the experience of negative reactions and high mastery lead to greater involvement in risky sexual behavior. Findings are interpreted within the theoretical framework of the coming-out process and gay identity formation.