Comparing current definitions of return to work: a measurement approach.

INTRODUCTION: Return-to-work (RTW) status is an often used outcome in work and health research. In low back pain, work is regarded as a normal activity a worker should return to in order to fully recover. Comparing outcomes across studies and even jurisdictions using different definitions of RTW can be challenging for readers in general and when performing a systematic review in particular. In this study, the measurement properties of previously defined RTW outcomes were examined with data from two studies from two countries. METHODS: Data on RTW in low back pain (LBP) from the Canadian Early Claimant Cohort (ECC); a workers' compensation based study, and the Dutch Amsterdam Sherbrooke Evaluation (ASE) study were analyzed. Correlations between outcomes, differences in predictive validity when using different outcomes and construct validity when comparing outcomes to a functional status outcome were analyzed. RESULTS: In the ECC all definitions were highly correlated and performed similarly in predictive validity. When compared to functional status, RTW definitions in the ECC study performed fair to good on all time points. In the ASE study all definitions were highly correlated and performed similarly in predictive validity. The RTW definitions, however, failed to compare or compared poorly with functional status. Only one definition compared fairly on one time point. CONCLUSIONS: Differently defined outcomes are highly correlated, give similar results in prediction, but seem to differ in construct validity when compared to functional status depending on societal context or possibly birth cohort. Comparison of studies using different RTW definitions appears valid as long as RTW status is not considered as a measure of functional status.

Prognostic factors for disability claim duration due to musculoskeletal symptoms among self-employed persons.

BACKGROUND: Employees and self-employed persons have, among others, different personal characteristics and different working conditions, which may influence the prognosis of sick leave and the duration of a disability claim. The purpose of the current study is to identify prognostic factors for the duration of a disability claim due to non-specific musculoskeletal disorders (MSD) among self-employed persons in the Netherlands. METHODS: The study population consisted of 276 self-employed persons, who all had a disability claim episode due to MSD with at least 75% work disability. The study was a cohort study with a follow-up period of 12 months. At baseline, participants filled in a questionnaire with possible individual, work-related and disease-related prognostic factors. RESULTS: The following prognostic factors significantly increased claim duration: age > 40 years (Hazard Ratio 0.54), no similar symptoms in the past (HR 0.46), having long-lasting symptoms of more than six months (HR 0.60), self-predicted return to work within more than one month or never (HR 0.24) and job dissatisfaction (HR 0.54). CONCLUSIONS: The prognostic factors we found indicate that for self-employed persons, the duration of a disability claim not only depends on the (history of) impairment of the insured, but also on age, self-predicted return to work and job satisfaction.

Dose-response relation between physical activity and sick leave.

OBJECTIVE: To investigate the dose-response relation between moderate and vigorous physical activity and sick leave in a working population. METHODS: Data were used from three large Dutch databases: two continuous, cross sectional surveys among a representative sample of the Dutch population and one prospective cohort study. A distinction was made between duration, frequency and intensity of physical activity. The outcome measure was the number of days of sick leave. Analyses of variance were used to compare sick leave (in days) for workers with different amounts of physical activity, in particular workers meeting the physical activity recommendations v those who did not. Linear and logistic regression analyses were used to obtain effect estimates in the prospective cohort study, with the generalised estimating equation (GEE) method. RESULTS: No relation was found between moderate physical activity and sick leave. In two databases, workers meeting the recommendation of vigorous physical activity (active at a vigorous level for at least three times a week) had significantly less sick leave: more than one day over two months and more than four days over a year. The duration of vigorous physical activity was not associated with sick leave. CONCLUSION: Physical activity at a vigorous intensity level for at least three times a week, as in the CDC/ACSM recommendation, has a positive effect on sick leave.

Participatory ergonomics as a return-to-work intervention: a future challenge?

BACKGROUND: Participatory ergonomics (PE) are often applied for prevention of low back pain (LBP). In this pilot-study, a PE-program is applied to the disability management of workers sick listed due to LBP. METHODS: The process, implementation, satisfaction, and barriers for implementation concerning the PE-program were analyzed quantitatively and qualitatively for 35 workers sick listed 2-6 weeks due to LBP and their ergonomists. RESULTS: Two-hundred-and-seventy ergonomic solutions were proposed to the employer. They were targeted more at work design and organization of work (58.9%) than at workplace and equipment design (38.9%). They were planned mostly on a short-term basis (74.8%). Almost half (48.9%) of the solutions for work adjustment were completely or partially implemented within 3 months after the first day of absenteeism. Most workers were satisfied about the PE-program (median score 7.8 on a 10-point scale) and reported a stimulating effect on return-to-work (66.7%). Main obstacles to implementation were technical or organizational difficulties (50.0%) and physical disabilities of the worker (44.8%). CONCLUSIONS: This study suggests that compliance, acceptance, and satisfaction related to the PE-program were good for all participants. Almost half of the proposed solutions were implemented.

Avoidance as a predictor of the biological course of HIV infection over a 7-year period in gay men.

The present study prospectively investigated the relation between avoidance coping and active cognitive and behavioral coping and the progression of HIV infection over 7 years in 181 gay men. Findings revealed that for a number of medical and behavioral factors, (a) avoidance coping predicted a lower rate of decline in CD4 cells, (b) the proportional hazard (PH) attributable to avoidance of developing a syncytium-inducing HIV variant was 0.72 (95% confidence interval [CI]: 0.53 - 0.99, p < .05), and (c) the PH attributable to avoidance of dropping below 200 CD4 cells/microl was 0.66 (95% CI: 0.50 - 0.89, p < .01). Avoidance coping was not related to the development of AIDS-defining clinical symptoms. Active cognitive and behavioral coping was not related to the outcome measures.

Homosexual encounters in different venues.

We aim to provide empirical data regarding the role of various sex-on-premises venues for gay men in the spread of HIV infection and homosexual activity with casual partners at different (public) venues was assessed. A questionnaire was filled out by participants in a cohort study in Amsterdam, The Netherlands. Questions were asked regarding sex in private homes, baths, cruising areas, darkrooms, cinemas, and hotel rooms. The majority of the 410 men who had sex with casual partners had done so in private homes (67.8%). However, cruising areas, baths and darkrooms were also highly frequented. Three general 'scenes' of venues frequented could be distinguished, and characteristics of men frequenting different types of venues were found to differ. Men who reported unprotected anal sex did so for only one type of venue. Private homes were the locations where most men engaged in high-risk behaviours. However, the number of partners practising unprotected anogenital sex was highest in (semi) public venues.

Differences in perception of risk for HIV infection with steady and non-steady partners among homosexual men.

In this study it was assessed whether homosexual men who practiced unprotected anogenital intercourse with steady and non-steady partners subjectively perceived their behaviors to be risky. Data were collected from 165 homosexual participants in an ongoing cohort study who reported unprotected anal sex. A variety of psychological factors which could possibly explain why some men were at risk but did not perceive their behavior as such, were investigated. This study showed that the majority of men who engaged in sexual risk behaviors within their primary relationship did not subjectively appraise their behavior as risky. The factors found to explain this discrepancy were not having had sex with a partner known to be HIV infected or to have AIDS (for couples of unknown serostatus) and not having had friends or relatives who were ill or had died (for seronegative couples). Homosexual men who had unprotected anal sex with casual partners generally were aware of the risk involved in their behavior.

Increase in safe sex among the young and non-monogamous: knowledge, attitudes and behavior regarding safe sex and condom use in The Netherlands from 1987 to 1993.

In 1987, the Dutch STD Foundation started several safe sex campaigns targeting the general population. These campaigns have been accompanied by surveys which were conducted every 6 months. Questions were asked about knowledge, attitudes and behavior. The number of people who regard condom use as being a safe sex practice increased over the years, as did the number of people who know that condoms protect against STDs and AIDs. Surprisingly, no accompanying changes in attitudes occurred. Nevertheless, the number of people saying they have done something to prevent HIV infection increased significantly among the young and non-monogamous. Also, specifically in these groups, both actual and intentional condom use increased remarkably. Although it is encouraging that those towards whom the campaigns were particularly directed, show the largest changes, there are also signs that these behavioral changes are levelling off.

Evaluation of a safe sex campaign regarding AIDS and other sexually transmitted diseases among young people in The Netherlands.

During the summer of 1989 a mass media campaign against the spread of AIDS and other sexually transmitted diseases (STDs) was launched in The Netherlands. The campaign was directed at young people and targeted inappropriate beliefs about the transmission of HIV and STDs. These inappropriate beliefs were considered to function as rationalizations and excuses for individuals and their sexual partners not to take preventive measures. To evaluate the campaign, young people who had noticed the campaign were compared with the ones interviewed at the pre-test. The ones that had not noticed the campaign served as a quasi-experimental control group. The campaign not only reached a sizeable majority of young people, but also succeeded in bringing about some of the desired changes. The risk of HIV infection became personally more relevant to the exposed group and several misconceptions or excuses were less often endorsed. This suggests that a mass media campaign does not have to be restricted to mere attention-raising and increasing factual knowledge, but may be of relevance for other psychosocial processes as well.

Risk factors and changes in sexual behavior in male homosexuals who seroconverted for human immunodeficiency virus antibodies.

In Amsterdam, The Netherlands, a cohort of 982 homosexual and bisexual men has been studied since 1984. Of these, 238 men had antibodies to the human immunodeficiency virus at the onset of the study, and 84 men seroconverted while under study. For each of these seroconversions, two participants who remained seronegative were chosen for comparison, taking the seroconversion date as a reference. This offered an opportunity to study any changes that may have occurred longitudinally, i.e., over time. Risk factors for seroconversion were studied along with changes in sexual behavior relative to the moment of seroconversion. The number of different partners in anogenital receptive intercourse and a history of syphilis or anogenital herpes simplex were found to be predictors for human immunodeficiency virus seroconversion. The data suggest that, prior to seroconversion, there is a peak in riskful sexual behavior and that the "decline" often observed immediately after seroconversion is, in fact, an indication of a return to "normal" sexual activity.

Risk factors for progression of human immunodeficiency virus (HIV) infection among seroconverted and seropositive homosexual men.

For identification of risk factors for progression of human immunodeficiency virus (HIV) infection, 746 homosexual men participating in a cohort study in Amsterdam, The Netherlands, were studied since October 1984. A total of 234 of these men were HIV antibody-positive at baseline, and 52 seroconverted during follow-up. These 286 individuals were categorized as high- and low-risk for progression to the acquired immunodeficiency syndrome (AIDS) on the basis of the presence or absence of HIV antigenemia, antibody to HIV core antigen, or a number of T helper lymphocytes less than 0.5 x 10(9)/liter during three or more subsequential blood samples. Ninety-six (41%) of the seropositives and 32 (62%) of those who seroconverted remained low-risk throughout the study period. Bivariate analyses revealed that educational level and a history of herpes zoster were associated with a low- and high-risk status, respectively. In multivariate analyses, a history of herpes zoster and a history of sexual intercourse with a person who had AIDS were associated with a more rapid disease progression. While herpes zoster is considered to be a marker of progressive immunodeficiency, a history of having sexual intercourse with a person who had AIDS points to the more virulent properties of HIV in these persons. Because both seropositives and seroconverters who had sexual intercourse with a person with AIDS had a more rapid disease progression, it seems plausible that being infected by a person with AIDS is a risk factor for a relative short incubation period.

AIDS in The Netherlands: the effects of several years of campaigning.

One of the primary aims of acquired immunodeficiency syndrome (AIDS) prevention campaigns in the Netherlands has been to inform the public of the facts about AIDS, thereby stimulating informed, but voluntary action to prevent transmission of the human immunodeficiency virus (HIV). By conducting successive population surveys from April 1987 until October 1989, the effects of this approach were assessed. Twice a year, approximately 1000 respondents, a random sample from the general population, were interviewed about AIDS and safe sex. Additionally, condom sales figures and STD incidences were evaluated. It appears that knowledge about the prevention of HIV transmission with condoms has reached 98% of the sample. During the study, there was an increase in the number of people who expressed an intention to use condoms or who already used them. Behaviour, however, appeared to fall short of intention. The observations were confirmed by condom sales figures and STD incidences. We conclude that the AIDS policy in the Netherlands has had beneficial effects, reflected by several indices.

[Decreased incidence in HIV infection and changed sex behavior in a cohort of homosexual men in Amsterdam]. / Lagere incidentie van HIV-infectie na veranderd seksueel gedrag in een cohort homoseksuele mannen te Amsterdam.

Prevalence and incidence of HIV were studied in two cohorts of homosexual men in Amsterdam between 1980 and 1987. The cumulative incidence of HIV infection increased from a weighted 2.2% in 1980 to 39% in 1987. In that year the observed incidence was less than 1%. The estimated annual HIV incidence was 3% in 1981, rose to 8.8% in 1984 and decreased gradually to 0% in 1987. This decline was assumed to be linked to a strong reduction of high risk sexual behaviour among the men under study.

Effect of human immunodeficiency virus (HIV) antibody knowledge on high-risk sexual behavior with steady and nonsteady sexual partners among homosexual men.

For the study of the impact of human immunodeficiency virus (HIV) antibody testing on high-risk sexual behavior with nonsteady and steady sexual partners, 307 homosexual men (118 seronegative, 75 seropositive, and 114 untested) were interviewed at three consecutive six-month intervals between July 1985 and December 1986. From the results, it appears that among seropositives the percentage who performed anogenital insertive intercourse with nonsteady partners remained constant (73, 64, and 61% during the first, second, and third intervals, respectively (nonsignificant]. Among seronegatives and those who were untested, the percentages who practiced anogenital receptive intercourse with nonsteady partners decreased from 44 to 29% and from 54 to 20%, respectively (p less than 0.05). The percentage who performed anogenital insertive intercourse and anogenital receptive intercourse with their steady partner remained constant in all groups: seropositives, +/- 70%; seronegatives, +/- 60%; and untested, +/- 55%. Seropositives were more likely to use condoms during anogenital insertive intercourse with their nonsteady and steady sexual partners than were seronegatives and untested persons during anogenital receptive intercourse with these partners (p less than 0.05). In the majority of cases, condoms were not used antibody testing in the three groups studied. The generalizability of these results, however, is limited.

Changes in sexual behaviour and the fall in incidence of HIV infection among homosexual men.

To investigate the epidemiology and normal course of infection with HIV the prevalence and incidence of the infection were studied among two cohorts of homosexual men in Amsterdam in 1980-7. The cumulative incidence of infection increased from a weighted 2.2% in 1980 to 39.0% in 1987. The estimated yearly incidence of HIV was 3.0% in 1981, rose to 8.8% in 1984, and fell gradually to 0% in 1987. During the study the sexual behaviour of the cohorts was examined. The number of men with whom anopenetrative intercourse was practised fell from a mean of 10.6 to 1.4 for those positive for HIV antibody, whereas the number with whom anoreceptive intercourse was practised fell from a mean of 3.7 to 0.5 for those negative for the antibody. In addition, there was a reduction in the number of cases of hepatitis B and syphilis among men in general. The decline in infection with HIV was assumed to be linked to changes in sexual behaviour. Such changes practised early in the course of the epidemic probably had a strong effect on the number of cases of AIDS among homosexual men in Amsterdam.

Impact of HIV antibody testing on changes in sexual behavior among homosexual men in The Netherlands.

Between October 1984 and May 1986, 746 homosexual men, living in and around Amsterdam, The Netherlands, were surveyed at three consecutive six months periods regarding their sexual behavior. At the start of the study all subjects, of whom 234 (31 per cent) were HIV-Ab seropositive, were informed about their HIV antibody status. Seropositives initially reported more sexual partners than seronegatives; they also showed a greater reduction in the number of sexual partners and the number of partners with whom all forms of sexual practices were performed than did seronegatives. In both groups subjects were more likely to terminate orogenital intercourse than anogenital intercourse and masturbation.

Failure rate of condoms during anogenital intercourse in homosexual men.

Two hundred and seventy seven homosexual men participating in an AIDS study in Amsterdam, The Netherlands, were interviewed in July to December 1986 regarding their experiences with the use of condoms during anogenital intercourse. It appeared that in many cases the condoms used could not be described as reliable, or were not used safely. In 8% (117/1468) of cases the condom tore or slipped off. When different condoms were compared, it was seen that "qualified" anal condoms functioned best. Other anal condoms functioned worse, and in many cases even worse than classic vaginal condoms. Whether these differences exclusively depended on differences in quality cannot be assessed. Men who buy a qualified anal condom are possibly more motivated and thus also less likely to have failures. Regarding the apparent unreliability of the condoms used, homosexual men are advised to refrain from anogenital intercourse. When this is not feasible, a qualified anal condom should be used.

Risk factors and prevalence of HIV antibodies in homosexual men in the Netherlands.

As part of the prospective AIDS study in Amsterdam, blood samples were collected from 741 healthy homosexual men with multiple sexual partners, between October 1984 and May 1985. Samples were analyzed for the presence of antibodies to the human immunodeficiency virus (anti-HIV). Anti-HIV was demonstrated in 233 (31%) of the respondents. Seropositive respondents engaged in anal receptive sexual techniques with more sexual partners than did seronegative respondents, whereas seronegatives engaged in manual sexual techniques with more sexual partners than did seropositives. As far as it was possible to control for the interrelations between the measured variables, a direct relation with anti-HIV was established. This leads to the conclusion that when the number of sexual partners is considered a risk factor for HIV, a clear distinction should be made between the sexual techniques practiced with these partners. Two other risk factors for the presence of anti-HIV were the use of cannabis and of nitrite.