Lethbridge LN, et al. - Data from multiple administrative data sets were compared and contrasted to study the 90-day surgical site infections (SSIs) rates for hip and knee arthroplasty in a single province from 2001 to 2015. Researchers hypothesized that SSI rates were being under-reported because of methodological biases. Combining administrative data sets symbolized that hospital-based data underestimate SSI rates by 0.44 of a percentage point overall years, a clinically important outcome provided the overall infection rate of 2.2% over the period. Less than 50% of hip and knee arthroplasty was registered as infected by 30 days and nearly 75% of cases were reported as infected by 90 days. In conclusion, SSI rates are underestimated by single-source administrative data sets and short follow-up periods. Moreover, to more precisely track SSI rates in hip and knee arthroplasty, administrative data sets should be combined and a minimum follow-up period of 90 days should be used.