Diagnosing Serious Infections in Older Adults Presenting to Ambulatory Care: a Systematic Review

Objectives: to summarise all available evidence on the accuracy of clinical features and blood tests for diagnosing serious infections in older patients presenting to ambulatory care.

Methods: systematic review, searching seven databases using a comprehensive search strategy. We included cross-sectional prospective diagnostic studies on (1) clinical features, (2) diagnostic prediction rules based on clinical features alone, (3) blood tests and (4) diagnostic prediction rules combining clinical features and blood tests. Study participants had to be community-dwelling adults aged ≥65 years, in whom a physician suspected an infection. We used QUADAS-2 to assess risk of bias. We calculated measures of diagnostic accuracy and present descriptive statistics.

Results: out of 13,757 unique articles, only six studies with a moderate to high risk of bias were included. There was substantial clinical heterogeneity across these studies. Clinical features had LR- ≥0.61 and LR+ ≤4.94. Twelve prediction rules using clinical features had LR- ≥0.30 and LR+ ≤2.78. There was evidence on four blood tests of which procalcitonin was the most often investigated: levels <0.37 ng/ml (LR- = 0.20; 95%CI 0.10-0.42) were suitable to rule out sepsis in moderately high prevalence situations. Two diagnostic prediction rules combining clinical features and procalcitonin had LR- of ≤0.12 (95%CI 0.05-0.33) and LR+ of maximum 1.39 (95%CI 1.30-1.49).

Conclusions: we found few studies on the diagnostic accuracy of clinical features and blood tests to detect serious infections in older people presenting to ambulatory care. The risk of bias was mostly moderate to high, leading to substantial uncertainty.