Added value of non-contrast CT for the diagnosis of acute pyelonephritis in older patients with suspected infection with an unknown focus: a retrospective diagnostic study.

OBJECTIVES: In older patients, the diagnosis of acute pyelonephritis (APN) is challenging. The aim was to evaluate the added value of CT to history, physical examination and urinalysis for the diagnosis of APN in older patients with suspected infection with an unknown focus. DESIGN: Retrospective diagnostic study. SETTING: Department of General Medicine in an acute care hospital in Japan. PARTICIPANTS: Patients aged ≥65 years who underwent blood cultures, a urine culture, and chest and abdominal CT to detect the focus of infection were included. PRIMARY OUTCOME MEASURES: Two radiologists independently reviewed four non-contrast CT signs: perirenal fat stranding, pelvicalyceal wall thickening, enlargement of the kidney and thickening of Gerota's fascia. Findings on contrast-enhanced CT could not be evaluated due to an insufficient number of patients in whom contrast-enhanced CT was performed. An expert panel was used as the reference standard for APN. The added value of CT findings was quantified by comparing the diagnostic performance between a model based on 10 predictors available before CT and an extended model including the CT findings. RESULTS: Of 473 patients, 61 (14.8%) were diagnosed with APN. When the laterality of the CT findings was taken into account, the model fit was not improved by adding them. In the laterality-insensitive analysis, the model performance was significantly improved by adding the CT signs (likelihood-ratio test p=0.03; c-index 0.89 vs 0.91, p=0.03). However, their clinical utility was only to improve the classification of 11.5% of patients with APN. CONCLUSIONS: The added value of non-contrast CT findings to history, physical examination and urinalysis was limited for the diagnosis of APN in older patients with a suspected infection with an unknown focus.

Usefulness of computed tomography in the diagnosis of acute pyelonephritis in older patients suspected of infection with unknown focus.

BACKGROUND: In older adults, the diagnosis of acute pyelonephritis is challenging because of non-specific symptoms and false-positive urine test results. Few studies have investigated the diagnostic performance of computed tomography (CT) signs. PURPOSE: To evaluate the diagnostic performance of CT signs for acute pyelonephritis in older patients suspected of infection with unknown focus. MATERIAL AND METHODS: This cross-sectional study was conducted between 2015 and 2018. Patients aged ≥65 years who underwent blood cultures, urine culture, and non-contrast or contrast-enhanced CT on admission were included. Cases with clinically presumable infection focus before CT were excluded. Two radiologists blinded to clinical information independently reviewed five CT signs: perirenal fat stranding; pelvicalyceal wall thickening and enhancement; renal enlargement; thickening of Gerota's fascia; and area(s) of decreased attenuation. The final diagnoses were made by a clinical expert panel. RESULTS: Among 473 eligible patients, 61 were diagnosed with acute pyelonephritis. When the laterality of findings between the left and right kidneys were considered, the positive and negative likelihood ratios of perirenal fat stranding were 4.0 (95% confidence interval [CI] = 2.3-7.0) and 0.8 (95% CI = 0.7-0.9) in non-contrast CT, respectively. The other signs in non-contrast CT showed similar diagnostic performance with positive and negative likelihood ratios of 3.5-11.3 and 0.8-0.9, respectively. CONCLUSION: CT signs can help physicians diagnose acute pyelonephritis in older patients suspected of infection with unknown focus.

Added value of inflammatory markers to vital signs to predict mortality in patients suspected of severe infection.

OBJECTIVE: To evaluate the added value of inflammatory markers to vital signs to predict mortality in patients suspected of severe infection. METHODS: This study was conducted at an acute care hospital (471-bed capacity). Consecutive adult patients suspected of severe infection who presented to either ambulatory care or the emergency department from April 2015 to March 2017 were retrospectively evaluated. A prognostic model for predicting 30-day in-hospital mortality based on previously established vital signs (systolic blood pressure, respiratory rate, and mental status) was compared with an extended model that also included four inflammatory markers (C-reactive protein, neutrophil-lymphocyte ratio, mean platelet volume, and red cell distribution width). Measures of interest were model fit, discrimination, and the net percentage of correctly reclassified individuals at the pre-specified threshold of 10% risk. RESULTS: Of the 1015 patients included, 66 (6.5%) died. The extended model including inflammatory markers performed significantly better than the vital sign model (likelihood ratio test: p < 0.001), and the c-index increased from 0.69 (range 0.67-0.70) to 0.76 (range 0.75-0.77) (p = 0.01). All included markers except C-reactive protein showed significant contribution to the model improvement. Among those who died, 9.1% (95% CI -2.8-21.8) were correctly reclassified by the extended model at the 10% threshold. CONCLUSIONS: The inflammatory markers except C-reactive protein showed added predictive value to vital signs. Future studies should focus on developing and validating prediction models for use in individualized predictions including both vital signs and the significant markers.