PYOGENIC LIVER ABSCESS IN OLDER PATIENTS: COMPARISON WITH YOUNGER PATIENTS

To the Editor: Pyogenic liver abscess is a serious infection. Epidemiology, underlying illness, pathogen, management, and mortality rate have all undergone significant changes over the past several decades.1,2 Pyogenic liver abscess has an increasing incidence in the world,1–3 and the mean age of patients with pyogenic liver abscess has increased.4,5 Pyogenic liver abscess remains a critical illness despite advances in diagnostic and therapeutic improvement,1–5 but few reports have specifically focused on older patients with pyogenic liver abscess in the past few years.4,5 Facing the growing aging population, more studies are needed for analysis of the clinical features and prognosis of older patients with pyogenic liver abscess. The aim of this study was to compare pyogenic liver abscess of older and younger adults and focus on the clinical features and outcome of this severe infection in older adults. This study was conducted in Chang Gung Memorial Hospital, a 3,300-bed medical center in northern Taiwan. A retrospective chart review was used to collect data. The charts of 610 patients with a diagnosis of pyogenic liver abscess from July 2002 to January 2008 were reviewed. The diagnosis of pyogenic liver abscess was established according to a combination of clinical, image, and positive bacterial culture from liver abscess. All 610 patients had positive bacterial culture from hepatic abscesses; 231 aged 65 and older were classified into the older group, and 379 younger than 65 were classified into the younger group for comparison. Clinical features, laboratory data, underlying medical illness, microbiological findings, therapeutic modalities, and outcomes of the two groups were compared. Thirty-day mortality was used as the outcome. The institutional review board at Chang Gung Memorial Hospital approved this study. The data were complied and analyzed using SPSS for Windows version 12.0 (SPSS, Inc., Chicago, IL). The mean age was 74.1 ± 8.0 (range 65–95) for the older patients and 51.1 ± 10.0 (range 16–64) for the younger patients. Comparison of clinical features is summarized in Table 1. Fever and chills were less frequent in older patients on admission. Frequency of biliary stones and malignancy was higher in older people, and alcoholism and cryptogenic origin of abscess were higher in younger patients. There was no significant difference in frequency of diabetes mellitus or liver cirrhosis between the two groups. Positive pus cultures of Klebsiella pneumoniae, Escherichia coli, Enterococcus, and polymicrobial abscess were more common in older than younger patients. Therapeutic procedures with percutaneous catheter drainage and surgical drainage and antibiotics treatment were similar between the two groups. The antibiotics most commonly used in older patients were ceftriaxone (78.0%) and cefazolin (13.4%) with or without metronidazole (38.0%). Length of hospitalization was longer for older patients (P=.02). Of the 610 patients enrolled, 38 died, yielding an overall mortality of 6.2%. Mortality was 9.5% in older patients and 4.2% in younger patients. Mortality was higher in older patients (P=.009). Malignancy and septic shock were the independent risk factors related to mortality in multivariate analysis. The main feature of this study was that all of the 610 patients obtained bacteria from liver abscess through computed tomography (CT), echo-guided aspiration, or surgical drainage. This article is the first study in which all patients had documented bacterial culture from hepatic abscess. This study included the largest numbers of hepatic abscesses cultured in older patients and is helpful for clinical evaluation of this serious infection. Fever and chills were less frequent in older than younger patients. Atypical clinical presentation is a possible explanation for absence of fever and chills in older patients with this severe infection, and physicians need to be alert for the diagnosis of this disease.4 Diabetes mellitus, biliary stones, malignancy, liver cirrhosis, and alcoholism were the risk factors for pyogenic liver abscess in older patients in this study. Because the prevalence of diabetes mellitus and malignancy have increased in older adults, the threat of pyogenic liver abscess in older patients is worthy of special attention. CT and ultrasound-guided percutaneous drainage has become the main treatment for patients with pyogenic liver abscess.1–5 This study showed that there was no significant difference in therapeutic procedures with drainage between these two groups and that the positive pus culture of K. pneumoniae and E. coli was more frequent in older than younger participants. This finding was different from previous reports of older patients in Western countries but consistent with the same finding in studies conducted in Asia.2,3,5–7 Ceftriaxone with or without metronidazole is the initial choice of therapy for the majority of older patients with pyogenic liver abscess, and then proper antimicrobial agents were selected according to the abscess culture, susceptibility test, and clinical course. Mortality was 6.2% overall and 9.5% in older patients in this study, which was lower than in previous report. The high awareness of symptoms and signs of the disease, earlier diagnosis with imaging and aspiration, aggressive catheter drainage of the abscess, and administration of proper antibiotics were probably the reasons for the low mortality.1,2,4,5 Pyogenic liver abscess with underlying malignant disease presented a poor prognosis.8 Malignancy and septic shock increased the mortality of pyogenic liver abscess and was consistent with the current study.8,9 The prognosis of pyogenic liver abscess might depend chiefly on the underlying illness and progression of severity of clinical condition.10 Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: All authors designed the study, collect the data, and prepared this letter. Sponsor's Role: None.