Concise Communication Antimicrobial utilization data: Does point prevalence data correlate with defined daily doses? Stephen B. Lee MD 1 , Daniel J.G. Thirion PharmD 3,4 , Neal Irfan PharmD 2 , Melani Sung PharmD 1,2 , Annie Brooks PharmD 1,2 , Fatimah Al-Mutawa MD 1 , Charles Frenette MD 4 and Dominik Mertz MD, MSc 1,2 1 McMaster University, Hamilton, Ontario, Canada, 2 Hamilton Health Sciences, Hamilton, Ontario, Canada, 3 Université de Montréal, Montréal, Quebec, Canada and 4 McGill University, Montreal, Quebec, Canada Abstract We correlated antibiotic consumption measured by point prevalence survey with defined daily doses (DDD) across multiple hospitals. Point prevalence survey had a higher correlation (1) with monthly DDDs than annual DDDs, (2) in nonsurgical versus surgical wards, and (3) on high- versus low-utilization wards. Findings may be hospital specific due to hospital differences. (Received 15 February 2019; accepted 12 May 2019) Antimicrobial resistance and the slow development of new drugs is a significant problem, making effective antimicrobial stewardship programs a priority. 1 Antibiotic utilization is a key quantitative metric of stewardship. In particular, days of therapy (DOT) and daily defined dose (DDD) are commonly accepted and used met- rics. 2 Point prevalence survey (PPS) of antibiotic use is a relatively short but resource-intensive metric used for cross-facility compari- son 3 in worldwide projects such as the Global Point Prevalence Survey of Antimicrobial Consumption and Resistance (Global PPS). 4 To the best of our knowledge, no study has compared PPS to the well-accepted DDD or DOT in acute-care hospitals. Hence, we aimed to assess the correlation between PPS and DDD. Methods In this study, 5 hospitals with a total of 48 wards conducted a Global PPS in 2017: 2 tertiary-care hospitals in Hamilton, Ontario (May 17 and August 1, 2017, respectively), and 3 hospitals in Montreal, Quebec (June 6, 2017). 4 We included a wide range of services such as medicine, surgery, intensive care, bone marrow transplantation, and solid organ transplantation. Emergency room and pediatric units were excluded. Global PPS entails collection of data on a given day for all hos- pitalized patients on systemic anti-infectives: antifungal, antiviral, and antibacterial with the exception of nystatin and sulfasalazine. We calculated the point prevalence by dividing the number of patients on any anti-infective by the number of patients on a spe- cific ward. The proportion calculated can be >1.0 if the average patient received >1 anti-infective. Dispensed antibiotics in DDD per 1,000 patient days were routinely collected at all sites using standard definitions and analyzed in monthly and annual groups. 5 Using the 48 wards as the unit of observation and with Pearson’s correlation (Microsoft Excel 2016, Redmond, WA), we assessed the association between the proportion of patients on antibiotics on the day of the PPS and the DDD per 1,000 patient days in the corre- sponding month of the PPS as well as the DDDs for the entire cal- endar year. 6 Finally, we conducted exploratory subgroup analyses based on hospital site, and type of ward. We grouped the wards into the bottom third, middle third, and highest third of utilization based on DDDs hypothesizing that wards with higher utilization have a stronger correlation due to less relative variance. Results Of 1,228 patients, 473 (39%) were on systemic anti-infectives across all sites (n = 138, 46%): 111 (33%) at the Hamilton sites, and 17 (27%), and 145 (44%) and 62 (35%) at the Montreal sites, respectively. The proportion of patients on anti-infectives by ward ranged from 0 to 100%. The DDD per 1,000 patient days ranged from 94.8 to 1,699.1 for the corresponding month of the PPS and from 160.6 to 1,700.8 for the annual consumption. The correlation coefficient (R) comparing PPS to the DDD per 1,000 patient days in the month of the PPS was 0.62 (Fig. 1a). The correlation coefficient was lower (R = 0.56) than the DDD per 1,000 patient days in the calendar year of the PPS (Fig. 1b). Most outliers were surgical units. When separated into surgical and medi- cal units, nonsurgical units correlated with an R of 0.63 for monthly and 0.57 for annual DDD, respectively, whereas surgical units had Rs of 0.57 and 0.52, respectively. The most extreme outliers were in Montreal: When surgical units were excluded at the 3 Montreal sites, the correlation coefficient was 0.29. At one of the Montreal hos- pitals, a surgical unit closed and surgical patients had been offloaded onto a medical unit, which likely explains this low R value. When we excluded this unit, the correlation coefficient increased to R = 0.57. The largest correlation coefficient was found at Hamilton sites in nonsurgical wards (R = 0.79). The volume of anti-infective use had a gradual effect on the correlation coefficient: Rs were 0.54 Author for correspondence: Dominik Mertz, E-mail: mertzd@mcmaster.ca Cite this article: Lee SB, et al. (2019). Antimicrobial utilization data: Does point prevalence data correlate with defined daily doses? Infection Control & Hospital Epidemiology, https://doi.org/10.1017/ice.2019.154 © 2019 by The Society for Healthcare Epidemiology of America. All rights reserved. Infection Control & Hospital Epidemiology (2019), 1–2 doi:10.1017/ice.2019.154