Defining the epidemiology of bloodstream infections: the 'gold standard' of population-based assessment

Abstract

Bloodstream infections (BSIs) are a major cause of morbidity and mortality. Although population-based studies have been proposed as an optimal means to define their epidemiology, the merit of these designs has not been well documented. This report investigated the potential value of using population-based designs in defining the epidemiology of BSIs. Population-based BSI surveillance was conducted in Calgary, Canada (population 1.24 million) and illustrative comparisons were made between the overall and selected subgroup cohorts within five main themes. The value of population denominator data, and age and gender standardization for calculation and comparison of incidence rates were demonstrated. In addition, a number of biases including those related to differential admission rates, selected hospital admission, and referral bias were highlighted in non-population-based cohorts. Due to their comprehensive nature and intrinsic minimization of bias, population-based designs should be considered the gold standard means of defining the epidemiology of an infectious disease.

Fig. 1.

Incident cases of bloodstream infection occurring in the Calgary area, 2000–2008.

Fig. 2.

Population demographics of the Calgary area, 2000–2008. (Source: Alberta Health Registry, Alberta Health Services.)

Fig. 3.

Population-based incidence of bloodstream infections occurring in the Calgary area, 2000–2008.

Fig. 4.

Population demographics of South Africa, 2011. (Source: Statistics South Africa.)

Fig. 5.

Hospital-acquired bloodstream infections/1000 discharges, Calgary, 2000–2008.

Fig. 6.

Population-based incidence of bloodstream infections by acquisition category, Calgary area, 2000–2008. CA, Community acquired; HCA, healthcare associated; HA, hospital acquired.