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M Zwahlen

Publications and source records attributed to M Zwahlen.

29 records · Page 2Linked to original sources
PubMed1997

Voluntary confidential HIV testing of STD patients in Switzerland, 1990-5: HIV test refusers cause different biases on HIV prevalences in heterosexuals and homo/bisexuals. Swiss Network of Dermatovenereology Policlinics.

OBJECTIVES: To monitor the prevalence of HIV infection among heterosexual and male homo/bisexual STD patients and assess the effect of HIV test refusers on the HIV prevalences. METHODS: A voluntary confidential HIV test was offered to all people diagnosed with an STD at the Swiss Network of Dermatovenerology Policlinics (SNDP) between July 1990 and June 1995. Anonymous sociodemographic and behavioural information was collected for each patient regardless of whether s/he accepted or refused the HIV test. RESULTS: The prevalence of HIV was 1.6% among heterosexuals and 22.4% homo/bisexual men and remained stable between July 1990 and June 1995. Refusal rates were 17.5% among heterosexuals and 16.0% among homo/bisexual men and did not change significantly over time. To assess the potential effect of HIV test refusers on the monitored HIV prevalences, we analysed test refusers by multivariate logistic regression. Among heterosexuals, refusal rates were significantly higher among patients with relatively low risk behaviours (patients reporting 0-1 sexual partners in the previous 6 months) while among homo/bisexual men they were significantly higher in those with high risk behaviours (patients reporting 10 or more sexual partners in the previous 6 months). CONCLUSIONS: We found high and stable HIV prevalences among patients treated for an STD at the SNDP. It appears that HIV test refusers biased HIV prevalences among heterosexuals and homo/bisexual men in different directions: in heterosexuals HIV prevalences were overestimated and in homo/bisexuals they were underestimated. A regular analysis of the characteristics of HIV test refusers should be an integral part of surveillance systems which use voluntary confidential HIV testing.

Bias↗
PubMed1995

[The extent of transfusion-associated HIV infections in Switzerland until 1994: an updated estimate].

OBJECTIVE: The first report on transfusion-associated HIV infections was published in the USA in 1982. The first case reports in Switzerland were published in 1986. So far there has never been a methodologically sound answer to the question of how many persons were infected with HIV by receiving transfusions in Switzerland before the introduction of universal HIV blood donor screening. METHODS: The following available data sources were analyzed simultaneously: firstly, the results of the look-back study conducted in 1993, secondly, the reports of HIV infections and AIDS cases in the national surveillance system, and, thirdly, the claims for compensation for HIV-infected transfusion recipients and hemophiliacs. Two methodologically different and independent estimates were obtained. Firstly, the coverage of the look-back study was estimated, which made it possible to calculate the total number of documentable transfusion-associated HIV infections in Switzerland. Secondly, matching was performed on the cases in the look-back study and the reports in the national surveillance system. Applying formulas of capture-recapture designs provided a second estimate of the total number of documentable transfusion-associated HIV infections. The claims for compensation were used to corroborate the estimates obtained. RESULTS: The two methods produced almost identical figures which were corroborated by the number of claims for compensation. It is therefore estimated that 80 to 100 persons in Switzerland may have been diagnosed as having HIV infection because of transfusions in Switzerland in the years after 1980. The last five known infections occurred in 1986 (four) and, after termination of the look-back study, in 1994 (one). However, the estimate of 80 to 100 does not include individuals who were infected before 1986 and died soon--within weeks or a few months--after the transfusion without diagnosis of HIV infection being possible. CONCLUSION: This estimate of the total number of transfusion-associated HIV infections in Switzerland is approximately half earlier published ones. In addition, the present study will probably reduce the remaining uncertainties about the size of these iatrogenic HIV infections in the 1980s.

Blood Component Transfusion↗
PubMed1995

Impact of the change from an injectable to a fully oral regimen on patient adherence to ambulatory tuberculosis treatment in Dar es Salaam, Tanzania.

OBJECTIVE: To measure the impact on patient adherence to directly observed ambulatory tuberculosis treatment substituting an all-oral treatment regimen for a regimen containing streptomycin. METHODS: The expected and observed attendance of patients during the intensive phase of anti-tuberculosis treatment was measured daily at two out-patient clinics in Dar es Salaam. During the observation period, treatment was changed from a regimen containing streptomycin to an all-oral regimen, and attendance proportions were compared for the three periods during which patients always, sometimes or never received streptomycin during the intensive phase of treatment. RESULTS: In Kinondoni, an average of 98 patients was expected every day, in Ilala 127. No significant difference was observed in attendance in Kinondoni between periods when patients always (median attendance 95.9%) and never (median 95.7%) received streptomycin injections as part of their intensive phase treatment for tuberculosis. In Ilala, no difference was noted in attendance between the period in which patients received streptomycin for at least part of their treatment (median 91.3%) and the period when ethambutol had fully replaced streptomycin (median 91.8%). CONCLUSIONS: In these two districts of Dar es Salaam, patient adherence to a completely oral treatment regimen was indistinguishable from that to a streptomycin-containing regimen. Given the potential of iatrogenic transmission of HIV and the advantages in reduced staff time and drug costs, the results clearly justify the replacement of streptomycin with ethambutol in Tanzania for new patients receiving an ambulatory rifampicin-containing regimen.

Administration, Oral↗
PubMed1990

[Epidemiology of tuberculosis in Switzerland].

Mortality for tuberculosis declined from an average of 7.5% per year in 1952 to 1.7 in 1988, tuberculosis incidence declined by 5 to 6% per year since 1945 to 17.4% in 1988, and the annual risk of infection declined by 11.4% per year since 1945 to 10.9 per 100,000 inhabitants respectively. The crude prevalence of tuberculous infection in the Swiss population is estimated to be 22.3% for the year 1990. The age-specific prevalence of infection is mirrored in age-specific morbidity. Among Swiss citizens, tuberculosis has become a disease of the elderly and is on the brink of elimination. In contrast, tuberculosis among foreigners (40% of cases in 1988) occurs mainly among the young who experience a more than 10-fold elevated risk compared to their Swiss age peers. These data suggest that case-finding and contact investigations are the major intervention tools against tuberculosis in the Swiss population. The increased tuberculosis risk among foreigners and the young age of these patients suggest that identification of those at high risk and their preventive treatment will have to be pursued actively.

Adolescent↗
PubMedDate not supplied

Condom use among patients attending six sexually transmitted disease clinics in Switzerland.

BACKGROUND AND OBJECTIVES: Persons treated for a sexually transmitted disease have been shown to be at increased risk for human immunodeficiency virus infection. Levels of condom use among these patients are presented, and sociodemographic and behavioral factors associated with self-reported never use of condoms are analyzed. STUDY DESIGN: This was a cross-sectional study of 2,257 patients treated at six sexually transmitted disease clinics in Switzerland between July 1990 and December 1992. RESULTS: Overall, 46.3% of the patients reported that they had never used condoms. Among heterosexual men, this level was 48.3% (n = 1,751), among homosexual and bisexual men it was 21.6% (n = 268), and among heterosexual women it was 60.1% (n = 238). In a logistic multivariate regression analysis, factors significantly associated with never use of condoms among heterosexual men included age over 29 years, not of Swiss origin, low level of education, few partners in the previous 6 months, contraction of the sexually transmitted disease from a stable partner, and not being an injecting drug user. CONCLUSION: These results document the high levels of condoms never being used in this population and highlight the importance of condom promotion activities provided by sexually transmitted disease clinics.

Adolescent↗