Age-related differences in symptoms, diagnosis and prognosis of bacteremia

Abstract

BackgroundElderly patients are at particular risk for bacteremia and sepsis. Atypical presentation may complicate the diagnosis. We studied patients with bacteremia, in order to assess possible age-related effects on the clinical presentation and course of severe infections.MethodsWe reviewed the records of 680 patients hospitalized between 1994 and 2004. All patients were diagnosed with bacteremia, 450 caused by Escherichia coli and 230 by Streptococcus pneumoniae. Descriptive analyses were performed for three age groups (< 65 years, 65–84 years, ≥ 85 years). In multivariate analyses age was dichotomized (< 65, ≥ 65 years). Symptoms were categorized into atypical or typical. Prognostic sensitivity of CRP and SIRS in identifying early organ failure was studied at different cut-off values. Outcome variables were organ failure within one day after admission and in-hospital mortality.ResultsThe higher age-groups more often presented atypical symptoms (p <0.001), decline in general health (p=0.029), and higher in-hospital mortality (p<0.001). The prognostic sensitivity of CRP did not differ between age groups, but in those ≥ 85 years the prognostic sensitivity of two SIRS criteria was lower than that of three criteria. Classical symptoms were protective for early organ failure (OR 0.67, 95% CI 0.45-0.99), and risk factors included; age ≥ 65 years (OR 1.65, 95% CI 1.09-2.49), comorbid illnesses (OR 1.19, 95% CI 1.02-1.40 per diagnosis), decline in general health (OR 2.28, 95% CI 1.58-3.27), tachycardia (OR 1.50, 95% CI 1.02-2.20), tachypnea (OR 3.86, 95% CI 2.64-5.66), and leukopenia (OR 4.16, 95% CI 1.59-10.91). Fever was protective for in-hospital mortality (OR 0.46, 95% CI 0.24-0.89), and risk factors included; age ≥ 65 years (OR 15.02, 95% CI 3.68-61.29), ≥ 1 comorbid illness (OR 2.61, 95% CI 1.11-6.14), bacteremia caused by S. pneumoniae (OR 2.79, 95% CI 1.43-5.46), leukopenia (OR 4.62, 95% CI 1.88-11.37), and number of early failing organs (OR 3.06, 95% CI 2.20-4.27 per failing organ).ConclusionsElderly patients with bacteremia more often present with atypical symptoms and reduced general health. The SIRS-criteria have poorer sensitivity for identifying organ failure in these patients. Advanced age, comorbidity, decline in general health, pneumococcal infection, and absence of classical symptoms are markers of a poor prognosis.

Bloodstream infections in older patients

“…23 Altered mental status is reported in several studies to occur in as high as »50% of patients 65 y and older. 23,25,28,29 Other studies reported altered mental status in 12-17% in patients aged 65 y and older 17,20,22 and 21-26% in patients 85 y and older. 20,22 The variability, at least in part, can be explained by various definition of "altered mental status" (Table 2).…”

“…Leukocytosis is reported in 39-73% of patients aged 65 and older 17,[21][22][23]25,28 and in one study was more common than in younger patients and with higher median values. 23 Leukopenia is described in »10% of patients in most studies 17,20,22,25,28 and its prevalence is not significantly different than in younger patients.…”

“…23 Leukopenia is described in »10% of patients in most studies 17,20,22,25,28 and its prevalence is not significantly different than in younger patients. 17,20,22 Acute kidney injury is reported to be more common in older than younger patients in some studies, 11,20,23 although not all. 13,22 CRP >D 8 mg/dl was as common in older patients as in younger patients in one study, however median CRP levels in the group of patients aged 65-74 y were significantly lower compared to younger patients.…”

“…[17][18][19][20][21] In a recent large prospective study including 2605 patients aged 65 y and older with bacteremia, absence of fever was documented in 6.3%. 14 Moreover, in most studies no significant difference from younger patients is demonstrated in the prevalence of fever 17,19,20,22 or in median temperature on presentation. 23 Hypothermia is reported in 0.3-10%.…”

“…23 Hypothermia is reported in 0.3-10%. 17,20,22,24,25 Definition of fever and site of measurement influence the results. Darwosky et al found that in patients aged 70 y and older sublingual temperature readings detect about one-third of fevers and that rectal temperature measurement will detect fever in up to 86% of infected patients.…”