Does Surveillance Bias Influence the Validity of Measures of Inpatient Complications? A Systematic Review

Surveillance bias may threaten the accuracy of inpatient complication measures. A systematic literature review was conducted to examine whether surveillance bias influences the validity of selected Patient Safety Indicator– and health care associated infection–related measures. Ten venous thromboembolism (VTE) articles were identified: 7 trauma related, 3 postoperative, and 1 central line–associated bloodstream infection (CLABSI) article. Nine VTE articles found positive associations between deep vein thrombosis imaging and VTE diagnoses. Because imaging also may be symptom driven, most studies performed additional analyses to corroborate findings. Six trauma-related and 2 postoperative VTE studies concluded that surveillance bias was present, the latter based on circumstantial evidence. The non-VTE study found a significant positive correlation between surveillance aggressiveness and intensive care unit CLABSI rates. Even considering VTE, relatively little is known about the impact of surveillance bias on inpatient complication measures. Given the implications of misclassifying hospitals on quality, this issue requires further investigation using more direct measurement methods.