Increased risk of incident primary cancer after Staphylococcus aureus bacteremia: A matched cohort study.

Susceptibility to infectious disease may be a marker of immunodeficiency caused by unrecognized cancer. To test the hypothesis, the risk of incident primary cancer was estimated among survivors of Staphylococcus aureus bacteremia (SAB) and compared to a random population cohort.Nation-wide population-based matched cohort study. Cases of SAB were identified from a national database and incident primary cancers were ascertained by record linkage. Incidence rate (IR) and ratio (IRR) with 95% confidence interval (CI) of 27 cancers was calculated by Poisson regression.During the first year of follow-up, 165 and 943 incident cases of cancer occurred in the case cohort (n = 12,918 (1.3%)) and the population cohort (n = 117,465 (0.8%)) for an IR of 3.78 (3.22-4.40) and 2.28 (2.14-2.43) per 100,000 person-years. The IRR was 1.65 (1.40-1.95). Of 27 cancers, 7 cancers occurred more frequently amongst cases than controls: cervical cancer (IRR 37.83 (4.23-338.47)), multiple myeloma (IRR 6.31 (2.58-15.44)), leukemia (IRR 4.73 (2.21-10.10)), sarcoma (IRR 4.73 (1.18-18.91)), liver cancer (IRR 3.64 (1.30-10.21)), pancreatic cancer (IRR 2.8 (1.27-6.16)), and urinary tract cancer (IRR 2.58 (1.23-5.39)). Compared to the control population, the risk of cancer was higher for those without comorbidity and with younger age. The overall risk of cancer during 2 to 5 years of follow-up was not increased (IRR 0.99 (95% CI: 0.89-1.11). However, the risk of pharyngeal cancer was increased (IRR 1.88 (1.04-3.39)) and the risk of liver cancer remained increased (IRR 3.93 (2.36-6.55)).The risk of primary incident cancer was 65% higher in the SAB cohort compared to the population cohort during the first year of follow-up and included 7 specific cancers. The risk was higher for those without comorbidity and with younger age. Screening for these specific cancers in selected populations may allow for earlier detection.

Long-term mortality and causes of death associated with Staphylococcus aureus bacteremia. A matched cohort study.

OBJECTIVES: Data describing long-term mortality in patients with Staphylococcus aureus bacteremia (SAB) is scarce. This study investigated risk factors, causes of death and temporal trends in long-term mortality associated with SAB. METHODS: Nationwide population-based matched cohort study. Mortality rates and ratios for 25,855 cases and 258,547 controls were analyzed by Poisson regression. Hazard ratio of death was computed by Cox proportional hazards regression analysis. RESULTS: The majority of deaths occurred within the first year of SAB (44.6%) and a further 15% occurred within the following 2-5 years. The mortality rate was 14-fold higher in the first year after SAB and 4.5-fold higher overall for cases compared to controls. Increasing age, comorbidity and hospital contact within 90 days of SAB was associated with an increased risk of death. The overall relative risk of death decreased gradually by 38% from 1992-1995 to 2012-2014. Compared to controls, SAB patients were more likely to die from congenital malformation, musculoskeletal/skin disease, digestive system disease, genitourinary disease, infectious disease, endocrine disease, injury and cancer and less likely to die from respiratory disease, nervous system disease, unknown causes, psychiatric disorders, cardiovascular disease and senility. Over time, rates of death decreased or were stable for all disease categories except for musculoskeletal and skin disease where a trend towards an increase was seen. CONCLUSION: Long-term mortality after SAB was high but decreased over time. SAB cases were more likely to die of eight specific causes of death and less likely to die of five other causes of death compared to controls. Causes of death decreased for most disease categories. Risk factors associated with long-term mortality were similar to those found for short-term mortality. To improve long-term survival after SAB, patients should be screened for comorbidity associated with SAB.

Increased risk of arterial thromboembolic events after Staphylococcus aureus bacteremia: A matched cohort study.

OBJECTIVES: An association between infection and arterial thromboembolic events (ATE) has been suggested. Here we examined the risk of myocardial infarction (MI), stroke and other ATE after Staphylococcus aureus bacteremia (SAB). METHODS: Danish register-based nation-wide observational cohort study between 1995 and 2008 with matched control subjects from the general population. RESULTS: Within a year, 278 of 15,669 SAB patients and 2570 of 156,690 controls developed MI, stroke or another ATE. The incidence rates among SAB patients were highest within the first 30 days and decreased over a year. The adjusted relative risk of MI, stroke and other ATE during the first 30 days after SAB in patients compared to controls were 2.2 (95% CI: 1.6-3.1), 5.5 (95% CI: 3.8-8.3) and 15.5 (95% CI: 6.9-35), respectively. Compared to controls, the increased adjusted relative risk persisted for 30 days for MI, 180 days for stroke and one year for other ATE. Increasing age, hypertension, atrial flutter/fibrillation, prior ATE and endocarditis in SAB patients were associated with an increased risk of ATE. CONCLUSIONS: SAB was associated with a short-term increased risk of ATE that persisted longer dependent on type of event. Studies are warranted to investigate treatment strategies to diminish ATE after SAB.

Increased risk of venous thromboembolism within the first year after Staphylococcus aureus bacteraemia: a nationwide observational matched cohort study.

OBJECTIVES: Recent evidence suggests that there is an association between infection and venous thromboembolism (VTE). Here, we examined the risk of VTE after Staphylococcus aureus bacteraemia (SAB) compared to the risk in control subjects. DESIGN AND SETTING: Register-based nationwide observational cohort study of hospitalized patients and matched control subjects from the general population in Denmark between 1995 and 2008. RESULTS: Amongst 15 669 SAB cases and 156 690 controls, 182 and 511, respectively, experienced VTE within 1 year. The overall incidence rate (IR) of VTE amongst cases was highest within the first 30 days [IR of deep vein thrombosis (DVT), 39.3 (95% confidence interval (CI) 28.9-53.4)/1000 person-years (PYs); IR of pulmonary embolism (PE), 16.3 (95% CI 10.1-26.2)/1000 PYs]. IRs of DVT were particularly increased amongst cases with a previous diagnosis of VTE, community-acquired infection, a history of injection drug use and in younger age groups. The overall hazard ratio of VTE for cases compared to controls declined from 15.6 (95% CI 10.3-23.5) in the first 30 days after SAB to 4.5 (95% CI 3.2-6.2) from 181 to 365 days after infection. The increased risk of VTE amongst SAB patients persisted after excluding cases with identified VTE risk factors. CONCLUSIONS: There was a particularly high risk of VTE during the first month following an episode of SAB. The risk declined over time, but remained at a threefold increased level compared to control subjects, suggesting that there are shared risk factors for SAB and VTE. Patients with SAB and well-documented risk factors for VTE may benefit from thromboprophylaxis.

A nationwide study of comorbidity and risk of reinfection after Staphylococcus aureus bacteraemia.

BACKGROUND: Data on risk factors and rates of reinfection associated with Staphylococcus aureus bacteraemia (SAB) are sparse. METHODS: We conducted a nationwide cohort study of cases of SAB diagnosed between 1995 and 2008. Reinfection was defined as an episode of SAB more than 90 days after the initial episode of SAB. Comorbidity was evaluated by the Charlson Comorbidity Index (CCI). Cox proportional hazards modelling was used to estimate hazard rates (HR). RESULTS: Of 10,891 eligible patients, 774 (7.1%) experienced reinfection a median of 458 days (range 90-5021 days) after their primary SAB episode corresponding to a reinfection rate of 1459 (95% confidence interval (CI): 1357-1562) per 100,000 personyears. In multivariate analysis, sex, origin, a vascular or peritoneal device, endocarditis and comorbidity were associated with reinfection. The association was more than two-fold higher among patients in dialysis and for patients with severe comorbidity (CCI ≥ 2). HIV infection (Hazard ratio (HR) 6.18, 95% CI: 4.17-9.16), renal disease (HR 3.92, 95% CI: 3.22-4.78), diabetes with complications (HR 2.11, 95% CI: 1.69-2.62), diabetes without complications (HR 1.61, 95% CI: 1.34-1.93), mild (HR: 1.94, 95% CI: 1.36-2.76) and severe liver disease (HR 2.08, 95% CI: 1.08-4.03), peptic ulcer (HR 1.33, 95% CI: 1.03-1.72), and paraplegia (HR 2.15, 95% CI: 1.02-4.54) were each associated with an increased risk of reinfection. CONCLUSIONS: Patients with previous SAB have a 60-fold higher risk of SAB compared to the general population. Patients with HIV infection, renal disease, diabetes, liver disease, peptic ulcer and paraplegia had the highest rates of reinfection.