METHODS

From March through May 2017, we conducted a prospective study to evaluate additional costs for CPs at the University Hospital Basel, an 800-bed tertiary-care center in Switzerland. During the study period, we randomly chose 10 patients with ongoing CPs, who were hospitalized on any of our medical or surgical acute-care wards, for on-site observation of isolation activities. Patients with airborne precautions were not included in the study. The local ethics committee approved the study as part of a continuing quality improvement program.

For each of these 10 patients, the corresponding isolation activities were observed for 24 consecutive hours by infection practitioners and well-trained medical students who were situated in front of the patient’s room. During observation periods, materials used, and extra workload relating to CPs were prospectively recorded and itemized. Standard care activities were not included if they were not part of standard precautions recommended by the Centers for Disease Control and Prevention (CDC).Reference Siegel, Rhinehart, Jackson and Chiarello ¹

From the hospital’s perspective, direct costs of CPs were calculated per patient day based on the following cost items: (1) additional isolation materials, (2) additional cleaning and disinfection materials, (3) extra workload (differentiated by hospital staff category), and (4) one-off items.

All costs were calculated in Swiss francs and converted to US dollars using the exchange rate of April 1, 2017, which was close to 1:1 (1 Swiss franc=$0.9973). Material costs were calculated based on manufacturers’ catalog prices. Costs of extra workload were calculated per minute, stratified by hospital staff category and based on actual mean gross wages (including the employer’s social security contributions) in January–February 2017. The (direct) cost items, respective costs, and gross wages are presented in Supplementary Table S1.

Direct costs were defined as additional costs that were directly attributable to CPs: costs of additional materials used, labor, and all direct efforts relating to CPs.Reference Siegel, Rhinehart, Jackson and Chiarello ¹ Additional isolation and cleaning and disinfection materials were defined as any resources specifically used as part of the CPs.Reference Siegel, Rhinehart, Jackson and Chiarello ¹ Extra workload was defined as any activity of healthcare workers or hospital staff that were directly attributable to CPs (eg, donning gowns and gloves upon entering the patient’s room).Reference Siegel, Rhinehart, Jackson and Chiarello ¹ One-off costs (averaged for the individual length of CPs per case) were defined as any fixed costs arising at the first or last day of CPs that were linked to CPs, including actual costs of an intensified final room disinfection and curtain changes (ie, service charges) and estimated (ie, one-off) extra workload. A consensus estimate of one-off workload (fixed) was based on internal interviews: 30 minutes for infection preventionists, 30 minutes for nurses (preparation of patient room), and 5 minutes for each board-certified physician and resident. The daily compliance rate of hospital staff was defined as the proportion of hospital staff entering a patient room that carried out all CDC-recommended CPs upon entering and leaving the respective patient room.Reference Siegel, Rhinehart, Jackson and Chiarello ¹

After ten 24-hour observations, we stopped including further patients due to a low variability of daily direct costs of CPs in a predefined interim analysis. The mean direct costs per patient day totaled $158.90 (95% confidence interval [CI], $124.90‒$192.80; 1,000-fold bootstrap 95% CI, $126.70‒$193.20). All cost data are expressed as mean (95% CI) to ensure the comprehensibility of cost calculations; additionally, skewed cost data are presented as median (interquartile range [IQR]). We analyzed all data using SPSS software version 22 (IBM, Chicago, IL).