Reto Zihlmann


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Zihlmann

First Name

Reto

ORCID

0000-0002-7510-837X

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2023 - 20254
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Publications 1 - 4 of 4
  • Estimating habitual iodine intake and prevalence of inadequacy from spot urine in cross-sectional studies: a modeling analysis to determine the required sample size
    Item type: Journal Article
    Arns-Glaser, Leonie; Zihlmann, Reto; Gessler, Sara; et al. (2023)
    The American Journal of Clinical Nutrition
    Background: The habitual/usual iodine intake and the prevalence of iodine inadequacy may be estimated from spot urinary iodine concentrations in cross-sectional studies by collecting a repeat spot urine in a subgroup of the study population and accounting for within-person variability in iodine intake. However, guidance on the required overall sample size (N) and the replicate rate (n) is lacking. Objectives: To determine the sample size (N) and replicate rate (n) needed to estimate the prevalence of iodine inadequacy in cross-sectional studies. Methods: We used data from local observational studies conducted in women 17–49 y old in Switzerland (N = 308), South Africa (N = 154), and Tanzania (N = 190). All participants collected 2 spot urine samples. We calculated the iodine intake using urinary iodine concentrations and accounted for urine volume using urinary creatinine concentration. For each study population, we estimated the habitual iodine intake distribution and determined the prevalence of iodine intake below the average requirement using the Statistical Program to Assess habitual Dietary Exposure (SPADE). We used the obtained model parameters in power analyzes and estimated the prevalence of iodine inadequacy for different sample sizes (N = 400, 600, and 900) and replicate rates (n = 50, 100, 200, 400, 600, and 900). Results: The estimated prevalence (95% CI) of inadequate iodine intake was 21% (15, 28%), 5.1% (1.3, 8.7%), and 8.2% (3.4, 13%) for Swiss, South African, and Tanzanian women, respectively. An N of 400 women, with a repeated measure (n) in 100 women, achieved a satisfactory precision of the prevalence estimate in all study populations. Increasing the replicate rate (n) improved the precision more effectively than increasing the N of the study. Conclusions: The sample size for cross-sectional studies aiming to assess the prevalence of inadequate iodine intake depend on the expected prevalence, the overall variance in intake, and the study design. However, an N of 400 participants with a repeated measure of 25% may be used as guidance when planning observational studies applying simple random sampling.
  • Identifying patients at high risk for multidrug-resistant organisms after hospitalization abroad
    Item type: Journal Article
    Bopp, Tamara C.; Marchesi, Martina; Zihlmann, Reto; et al. (2023)
    Infection Control & Hospital Epidemiology
    Objectives: We quantified the percentage of multidrug-resistant organism (MDRO) carriers among repatriated patients. We identified factors associated with MDRO carriage, and we evaluated the yield of MDRO detection per screened body site. Design: Retrospective cohort study. Setting: A tertiary-care center in Switzerland. Patients: Adult patients after a stay in a healthcare institution abroad. Methods: Patients were screened for MDRO carriage. Standard sites, including nose and throat, groins, and (since mid-2018) rectum, and risk-based sites (wounds, urine, tracheal secretion) were sampled. MDROs were defined as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing Enterobacterales (CPE), multidrug-resistant (MDR) Enterobacterales, and MDR nonfermenting gram-negative rods. Risk factors for MDRO carriage were assessed using multivariate logistic regression. Results: Between May 2017 and April 2019, 438 patients were screened and 107 (24.4%) tested positive for an MDRO, predominantly ESBL-producing and MDR Enterobacterales. Risk factors for MDRO colonization were the length of stay in hospital abroad, antibiotic treatment with 'Watch' and 'Reserve' antibiotics, and region of hospitalization abroad. Rectal swabs had the highest yield for detecting patients with MDR intestinal bacteria, but nose/throat and groins, or wound samples were more sensitive for MRSA or nonfermenting gram-negative organisms, respectively. Conclusions: We identified risk factors for MDRO carriage and body sites with the highest yield for a specific MDRO, which might help to target screening and isolation and reduce screening costs.
  • Impact of COVID-19 lockdown-associated visitor restrictions on mother-child interaction and emotional state of women in the puerperium – a retrospective cohort study
    Item type: Journal Article
    Höhn, Irina; Hernadi, Anett; Zihlmann, Reto; et al. (2025)
    Swiss Medical Weekly
    Introduction: The aim of this study was to analyse the impact of maternal isolation during the COVID-19 lockdown. Two main aspects were examined: (1) What impact do these social restrictions have on maternal depressive symptoms? and (2) Is there an influence on mother-child interaction? As secondary endpoints, we defined the influence of the restrictions on breastfeeding, the length of hospital stay, patient satisfaction during the inpatient stay due to the reduced number of visitors, and postpartum complications after discharge. Materials and Methods: The study was conducted at a university-affiliated teaching hospital in Switzerland. Women who delivered in the first phase of the COVID-19 pandemic and who were not allowed to have any visitors including the child’s father (group “total ban”, n = 53; 20 March 2020 to 10 May 2020) and women who were only allowed to have a visit from the child’s father (group “partial ban”, n = 49; 11 May 2020 to 20 June 2020) were compared to a reference group of women who delivered prior to the restrictions (n = 61; 1 January 2020 to 16 February 2020). Participants completed a questionnaire one year after delivery to assess their situation one week and one year after giving birth. The primary outcomes were the state of mental health (measured by the Edinburgh Postnatal Depression Scale) and maternal bonding (measured by the Mother-to-Infant-Bonding Scale). Secondary outcome measures were breastfeeding status, postpartum complications and length of hospital stay. Results: Of 404 women eligible for participation, 241 declined to participate or could not be reached. Obstetric baseline characteristics were similar across all three groups. Analysis of signs of depression showed a 2-fold higher risk of postpartum depression after one week and one year in both isolation groups compared to the reference group (23% and 20% vs 9% at one week; 11% and 11% vs 5% at one year). However, this did not reach sta tistical significance (p = 0.158; p = 0.471). Analysis of the Mother-to-Infant-Bonding Scale revealed similar scores in all groups in the first week and after 12 months. There were no significant differences in the rates of breastfeeding and postpartum complications. Hospital stays were clearly shorter during the partial and total visitor bans (3.06 days and 2.55 days vs 3.51 days in the reference group [p <0.001]). 45% of patients in the reference group would have been dissatisfied with a limitation to the number of visitors as compared to only 18% in the total and 9% in the partial visitor ban groups (p <0.001). Conclusions: We found an increased albeit non-statistically significant risk of postpartum depression one week and one year after delivery under different forms of isolation on the postpartum ward. We hypothesise that this is unlikely caused solely by isolation, as both groups were equally affected independently of the possibility of partner support. Maternal bonding and breastfeeding rates were unaffected. Hospital stays were significantly shorter during the partial and total visitor ban, but postpartum complications were unaffected. Only a minority of women in the isolation groups were dissatisfied with the visiting restrictions. The SARS-CoV-2-associated protective isolation measures applied in maternity wards appear not to have had a major negative impact on maternal wellbeing in this population.
  • Longitudinal increase in the detection rate of Mycobacterium chimaera in heater-cooler device-derived water samples
    Item type: Journal Article
    Schreiber, Peter Werner; Zihlmann, Reto; Schärer, Verena; et al. (2023)
    Journal of Hospital Infection
    Background: Colonization with Mycobacterium chimaera and other non-tuberculous mycobacteria (NTM) has been reported for heater-cooler devices (HCDs) produced by several manufacturers. Up until now, exclusively LivaNova (London, UK) HCDs have been associated with M. chimaera infections after cardiac surgery. The vast majority of studies on HCD colonization were cross-sectional. The vast majority of studies on HCD colonization were cross-sectional. Aim: We were interested in longitudinal dynamics of mycobacterial growth in HCD water samples and analysed data of a prospective mycobacterial surveillance of five LivaNova 3T HCDs. Methods: Five LivaNova HCDs were subjected to prospective mycobacterial surveillance. For each HCD and the total of HCDs, results of mycobacterial detection were analyzed. Logistic regression was applied to model the association between growth of any NTM or M. chimaera and duration of HCD use. Results: Non-tuberculous mycobacteria were isolated in 319 (48.0%, 21 water samples grew more than one mycobacterial species) of a total of 665 water samples. The most frequently detected species were M. chimaera (N = 247/319, 77.4%), Mycobacterium gordonae (46/319, 14.4%) and Mycobacterium paragordonae (34/319, 10.7%). Detection rates increased prospectively for any NTM (odds ratio (OR) per year in use: 1.60, 95% confidence interval (CI) 1.17–2.24, P<0.001) and for M. chimaera (OR per year in use: 1.67, 95% CI 1.11–2.57, P<0.01). Conclusion: Longer duration of HCD use was associated with higher detection rates for any NTM and M. chimaera, respectively.
Publications 1 - 4 of 4