Clinical characteristics and outcomes of community-acquired pneumonia in solid organ transplant recipients

BACKGROUND

Pneumonia is a frequent complication of solid organ transplantation that adversely impacts both graft and recipient survival. There is a paucity of data on community-acquired pneumonia (CAP) in transplant recipients, particularly the long term outcomes. We conducted a study to compare the clinical characteristics and outcomes of pneumonia in solid organ transplant (SOT) recipients to those in non-transplant (NT) recipients.

MATERIAL AND METHODS

Clinical characteristics were abstracted from electronic medical records. Outcomes included time to hospital discharge, short and long-term mortality. Inverse-propensity score weights were assigned to account for between-group differences. Adjusted analysis included a weighted logistic regression. Results were reported as odds ratios with a corresponding 95 % confidence interval (CI).

RESULTS

A total of 7449 patients were admitted with CAP. Patients were divided into two groups: SOT recipients 42 (0.56 %) and NT recipients 7396 (99.2 %). SOT recipients were younger, more commonly males, with higher prevalence of comorbidities. After accounting for inverse-propensity score weighting, the odds of mortality were higher in SOT recipients in hospital, at 30 days and at 1 year. The magnitude of increase in mortality for SOT recipients was greatest at 1 year with 1.41 (95 % CI: 1.38-1.44) times higher odds.

CONCLUSION

In patients with CAP, SOT recipients are younger, more commonly male and have more co-morbidities compared with NT recipients. They also have higher 1 year mortality after adjustment. Clinicians must be vigilant toward the pronounced long-term mortality risk among these patients and ensure continued follow-up care for them.

Leukopenia in autosomal dominant polycystic kidney disease: a single-center cohort of kidney transplant candidates with post-transplantation follow-up

Background

Autosomal dominant polycystic kidney disease (ADPKD) has occasionally been associated with lower peripheral white blood cell (WBC) counts. This study aimed to investigate the peripheral blood cell counts in a large cohort of kidney transplant recipients before and after kidney transplantation and its potential impact on post-transplant outcomes.

Methods

This was a retrospective study with long-term follow-up data of 2090 patients who underwent a first kidney transplantation in the Leuven University Hospitals, of whom 392 had ADPKD.

Results

In total, 2090 patients who underwent a first kidney transplantation in the Leuven University Hospitals were included, of whom 392 had ADPKD. Both pre- and post-transplantation, ADPKD patients had significantly lower total WBC counts, and more specifically lower neutrophil, lymphocyte and eosinophil counts compared with the non-ADPKD patients. This observation was independent of potential confounders such as level of inflammation, smoking habit, vitamins and pre-transplant medication. Overall survival and kidney transplant survival were significantly better in ADPKD vs non-ADPKD transplant recipients and a longer time to first infection was observed. However, no association between blood cell counts and outcome differences was found.

Conclusions

In conclusion, this large single-center study reports a strong and independent association between ADPKD and lower peripheral WBC counts both before and after kidney transplantation. Considering the role of inflammation in disease progression, further investigation into the role of WBC in ADPKD is needed.

Patients with transplantation have reduced mortality in bacteraemia: Analysis of data from a randomised trial

OBJECTIVES

Infection remains a major complication of organ transplantation. Paradoxically, epidemiological studies suggest better survival from serious infection. We analysed the relationship between organ transplantation and short -term mortality of patients with bloodstream infection.

METHODS

Data on transplantation status was extracted from a large prospective, multi-centre clinical trial in bloodstream infection. Logistic regression for 28-day mortality was performed on the whole cohort and a propensity-matched cohort (3:1). Infective pathogen, focus of infection, and clinical variables were included in the model. Mediation analysis was performed on clinical variables to explore causation.

RESULTS

4,178 participants were included in the full cohort, with 868 in the matched cohort, of which 217 received an organ transplant. Haematopoietic stem cell transplants (HSCT) were the most common transplant (n = 99), followed by kidney (n = 70). The most common pathogens were staphylococci and Enterobacterales. Transplantation status was associated with a reduced mortality in both the whole (Odds Ratio, OR 0.53; 95% CI 0.28, 0.77) and matched (OR 0.55, 95% CI 0.34, 0.90) cohort, while steroid use was robustly associated with increased mortality OR 4.4 (95% CI 3.12, 6.20) in the whole cohort and OR 5.24 (95% CI 2.79, 9.84) in the matched cohort. There was no interaction between steroid use and transplant status, so transplant patients on steroids generally had increased mortality relative to those without either.

CONCLUSIONS

Organ transplantation is associated with a near halving of short term mortality in bloodstream infection, including a cohort matched for comorbidities, infective pathogen and focus. Steroid usage is associated with increased mortality regardless of transplant status. Understanding the mechanism and causation of this mortality benefit should be a focus of future research.

Cytopenia in autosomal dominant polycystic kidney disease (ADPKD): merely an association or a disease-related feature with prognostic implications?

Autosomal dominant polycystic kidney disease (ADPKD) is associated with distinct cytopenias in observational studies; the most consistent and strongest association is seen with alternations in the lymphocytic lineages. Although the underlying mechanism of these associations is unclear, it has been hypothesized to be secondary to sequestration of white blood cells in cystic organs, or related to the uremic environment in chronic kidney disease (CKD). However, since mutations in PKD1 or -2 affect several immunomodulating pathways, cytopenia may well be an unrecognized extrarenal manifestation of ADPKD. Furthermore, many important questions on the clinical implications of this finding and the effect on the disease course in these patients are unanswered. In this review article, we provide an overview of the current evidence on cytopenia in ADPKD and explore the underlying mechanisms of this association and its potential prognostic implications. Based on the current literature, we hypothesize that polycystin deficiency can disturb immune cell homeostasis and that cytopenia is thus an intrinsic feature of ADPKD, related to genetic factors. Taken together, these findings warrant further investigation to establish the exact etiology and role of cytopenia in patients with ADPKD.

Time to positivity in bloodstream infection is not a prognostic marker for mortality: analysis of a prospective multicentre randomized control trial

OBJECTIVES

Time to positivity (TTP), calculated automatically in modern blood culture systems, is considered a proxy for microbial load and has been suggested as a potential prognostic marker in bloodstream infections. In this large, multicentre, prospectively collected cohort, our primary analysis aimed to quantify the relationship between the TTP of monomicrobial blood cultures and mortality.

METHODS

Data from a multicentre randomized controlled trial (RAPIDO) in bloodstream infection were analysed. Bloodstream infections were classified into 13 groups/subgroups. The relationship between mortality and TTP was assessed by logistic regression, adjusted for site, organism, and clinical variables, and linear regression was applied to examine the association between clinical variables and TTP. Robustness was assessed by sensitivity analysis.

RESULTS

In total 4468 participants were included in the RAPIDO. After exclusions, 3462 were analysed, with the most common organisms being coagulase-negative staphylococci (1072 patients) and Escherichia coli (861 patients); 785 patients (22.7%) died within 28 days. We found no relationship between TTP and mortality for any groups except for streptococci (odds ratio (OR) with each hour 0.98, 95%CI 0.96-1.00) and Candida (OR 1.03, 95%CI 1.00-1.05). There was large variability between organisms and sites in TTP. Fever (geometric mean ratio (GMR) 0.95, 95%CI 0.92-0.99), age (GMR per 10 years 1.01, 95%CI 1.00-1.02), and neutrophilia were associated with TTP (GMR 1.03, 95%CI 1.02-1.04).

CONCLUSIONS

Time to positivity is not associated with mortality, except in the case of Candida spp. (longer times associated with worse outcomes) and possibly streptococci (shorter times associated with worse outcomes). There was a large variation between median times across centres, limiting external validity.

Novel non-cystic features of polycystic kidney disease: having new eyes or seeking new landscapes

For decades, researchers have been trying to decipher the complex pathophysiology of autosomal dominant polycystic kidney disease (ADPKD). So far these efforts have led to clinical trials with different candidate treatments, with tolvaptan being the only molecule that has gained approval for this indication. As end-stage kidney disease due to ADPKD has a substantial impact on health expenditures worldwide, it is likely that new drugs targeting kidney function will be developed. On the other hand, recent clinical observations and experimental data, including PKD knockout models in various cell types, have revealed unexpected involvement of many other organs and cell systems of variable severity. These novel non-cystic features, some of which, such as lymphopenia and an increased risk to develop infections, should be validated or further explored and might open new avenues for better risk stratification and a more tailored approach. New insights into the aberrant pathways involved with abnormal expression of PKD gene products polycystin-1 and -2 could, for instance, lead to a more directed approach towards early-onset endothelial dysfunction and subsequent cardiovascular disease. Furthermore, a better understanding of cellular pathways in PKD that can explain the propensity to develop certain types of cancer can guide post-transplant immunosuppressive and prophylactic strategies. In the following review article we will systematically discuss recently discovered non-cystic features of PKD and not well-established characteristics. Overall, this knowledge could enable us to improve the outcome of PKD patients apart from ongoing efforts to slow down cyst growth and attenuate kidney function decline.

Infectious complications after kidney transplantation

Infectious complications are one of the leading causes of hospitalization and mortality in kidney transplant recipients. They are more frequent during the year following transplantation, and in the elderly. Community infections, such as pyelonephritis and pneumonia, are from far the most common infections. However, the field of opportunistic infections has been particularly moving as routine prophylaxis for cytomegalovirus and pneumocystosis have altered their patterns. Emergence of new infections, as BK nephritis, followed by chronic infections by Norovirus and E hepatitis, and increasing incidence of invasive fungal infections and mycobacterial infections have raised concerns. An increasing number of infections may be prevented by prophylaxis, but also by vaccines who should be encouraged, especially for influenza, pneumococcal diseases and zoster. Access to transplantation is now possible for human immunodeficiency virus infected patients, with good results. The field of infectious diseases is thus changing in kidney transplant recipients, due to high-risk recipients, new immunosuppressive drugs, and development of new diagnostic, therapeutic and preventive methods.

Hereditary polycystic kidney disease is characterized by lymphopenia across all stages of kidney dysfunction: an observational study

Background

Polycystic kidney disease (PKD) is characterized by urinary tract infections and extrarenal abnormalities such as an increased risk of cancer. As mutations in polycystin-1 and -2 are associated with decreased proliferation of immortalized lymphoblastoid cells in PKD, we investigated whether lymphopenia could be an unrecognized trait of PKD.

Methods

We studied 700 kidney transplant recipients with (n = 126) or without PKD at the time of kidney transplantation between 1 January 2003 and 31 December 2014 at Ghent University Hospital. We also studied 204 patients with chronic kidney disease (CKD) with PKD and 204 matched CKD patients without PKD across comparable CKD strata with assessment between 1 January 1999 and 1 February 2016 at three renal outpatient clinics. We compared lymphocyte counts with multiple linear regression analysis to adjust for potential confounders. We analysed flow cytometric immunophenotyping data and other haematological parameters.

Results

Lymphocyte counts were 264/µL [95% confidence interval (CI) 144-384] and 345/µL (95% CI 245-445) (both P < 0.001) lower in the end-stage kidney disease (ESKD) and CKD cohort, respectively, after adjustment for age, sex, ln(C-reactive protein) and estimated glomerular filtration rate (in the CKD cohort only). In particular, CD8+ T and B lymphocytes were significantly lower in transplant recipients with versus without PKD (P < 0.001 for both). Thrombocyte and monocyte counts were lower in patients with versus without PKD in both cohorts (P < 0.001 for all analyses except P = 0.01 for monocytes in the ESKD cohort).

Conclusion

PKD is characterized by distinct cytopenias and especially lymphopenia, independent of kidney function. This finding has the potential to alter our therapeutic approach to patients with PKD.

Irradiation enhanced risks of hospitalised pneumonopathy in lung cancer patients: a population-based surgical cohort study

OBJECTIVE

Pulmonary radiotherapy has been reported to increase a risk of pneumonopathy, including pneumonitis and secondary pneumonia, however evidence from population-based studies is lacking. The present study intended to explore whether postoperative irradiation increases occurrence of severe pneumonopathy in lung cancer patients.

DESIGN, SETTING AND PARTICIPANTS

The nationwide population-based study analysed the Taiwan National Health Insurance Research Database (covered >99% of Taiwanese) in a real-world setting. From 2000 to 2010, 4335 newly diagnosed lung cancer patients were allocated into two groups: surgery-RT (n=867) and surgery-alone (n=3468). With a ratio of 1:4, propensity score was used to match 11 baseline factors to balance groups.

INTERVENTIONS/EXPOSURES

Irradiation was delivered to bronchial stump and mediastinum according to peer-audited guidelines.

OUTCOMES/MEASURES

Hospitalised pneumonia/pneumonitis-free survival was the primary end point. Risk factors and hazard effects were secondary measures.

RESULTS

Multivariable analysis identified five independent risk factors for hospitalised pneumonopathy: elderly (>65 years), male, irradiation, chronic obstructive pulmonary disease (COPD) and chronic kidney disease (CKD). Compared with surgery-alone, a higher risk of hospitalised pneumonopathy was found in surgery-RT patients (HR, 2.20; 95% CI, 1.93-2.51; 2-year hospitalised pneumonia/pneumonitis-free survival, 85.2% vs 69.0%; both p<0.0001), especially in elderly males with COPD and CKD (HR, 13.74; 95% CI, 6.61-28.53; p<0.0001). Unexpectedly, we observed a higher risk of hospitalised pneumonopathy in younger irradiated-CKD patients (HR, 13.07; 95% CI, 5.71-29.94; p<0.0001) than that of elderly irradiated-CKD patients (HR, 4.82; 95% CI, 2.88-8.08; p<0.0001).

CONCLUSIONS

A high risk of hospitalised pneumonopathy is observed in irradiated patients, especially in elderly males with COPD and CKD. For these patients, close clinical surveillance and aggressive pneumonia/pneumonitis prevention should be considered. Further investigations are required to define underlying biological mechanisms, especially for younger CKD patients.

Risk and outcome of pyelonephritis among renal transplant recipients

Background

Urinary tract infection is the most common infectious disease requiring hospitalisation following renal transplantation. However, the risk and outcome of post-transplant pyelonephritis remains unclear.

Methods

This population-based cohort study was conducted from 1 January 1990 to 31 December 2009. Each member of a Danish population-based, nationwide cohort of first-time renal transplant recipients was matched by age and gender with up to 19 population controls. Information on hospital discharge diagnosis, emigration, and mortality was obtained from nationwide administrative databases. Individuals were observed from the date of first renal transplantation and until graft loss, emigration, or death. Risk factors were assessed by Poisson regression.

Results

The incidence rate (IR) of first-time hospitalisation for pyelonephritis was 18.5 (95 % confidence interval [CI]: 16.4–20.9) per 1,000 person-years of follow-up (PYFU) among renal transplant recipients (N = 2,656) and 0.26 (CI: 0.21–0.31) per 1,000 PYFU among population controls (N = 49,226) yielding an incidence rate-ratio (IRR) of 72.0 (95 % CI: 57.8–89.7). Among renal transplant recipients, the risk of pyelonephritis decreased during the entire study period and was lowest in 2005–09 (IRR = 0.46, CI: 0.31–0.68). The highest risk of pyelonephritis was observed within the first six months post-transplantation (IR = 69.9 per 1,000 PYFU; CI: 56.4–86.7). Other risk factors for post-transplant pyelonephritis included female gender, high Charlson comorbidity index score, HLA-DR mismatch, cause of renal failure, and calendar period. Interestingly, we found that the combined risk of graft loss and death was 45 %, (CI: 19–77 %) higher in renal transplant recipients following post-transplant pyelonephritis compared to those who had no admission due to pyelonephritis.

Conclusions

The risk of first-time hospitalisation for pyelonephritis among renal transplant recipients is high. Further, post-transplant pyelonephritis was associated with excess risk of graft loss and death; this indicates that strategies aimed at reducing upper urinary tract infections are likely to enhance renal graft survival.

American Society of Nephrology Quiz and Questionnaire 2015: Transplantation

The Nephrology Quiz and Questionnaire remains an extremely popular session for attendees of the Annual Kidney Week Meeting of the American Society of Nephrology. Once again, the conference hall was overflowing with audience members and eager quiz participants. Topics covered by the expert discussants included electrolyte and acid-base disorders, glomerular disease, ESRD/dialysis, and kidney transplantation. Complex cases representing each of these categories along with single best answer questions were prepared and submitted by the panel of experts. Before the meeting, training program directors of US nephrology fellowship programs and nephrology fellows answered the questions through an internet-based questionnaire. During the live session, members of the audience tested their knowledge and judgment on a series of case-oriented questions prepared and discussed by the experts. They compared their answers in real time using their cell phones with a special application with the answers of the nephrology fellows and training program directors. The correct and incorrect answers were then discussed after the results of the questionnaire were displayed. As always, the audience, lecturers, and moderators enjoyed this highly educational session. This article recapitulates the session and reproduces its educational value for the Clinical Journal of the American Society of Nephrology readers. Enjoy the clinical cases and expert discussions.

Usefulness of serum procalcitonin as a diagnostic biomarker of infection in children with chronic kidney disease

INTRODUCTION

Serum procalcitonin (PCT) levels are known to be low in healthy individuals in healthy subjects but are increased in patients with a severe bacterial infection. It has not been extensively studied in children with chronic kidney disease (CKD), treated either with hemodialysis (HD) or with renal transplantation.

MATERIAL AND METHODS

During a 6-month period, blood samples were taken from 102 (55 HD children and 47 renal transplant recipients) children with a strong clinical suspicion of infection. Procalcitonin levels were measured by ELISA.

RESULTS

Thirty-four/102 cases had proven infections as defined previously. Children with proven infections had a significantly higher PCT (0.920 ±0.24 ng/ml) than those without (0.456 ±0.53 ng/ml), p = 0.04. The ideal cutoff value derived for serum PCT was 0.5 ng/ml. This threshold value established a sensitivity of 94.1% and a specificity of 87.9%.

CONCLUSIONS

This study indicates that significantly increased PCT concentration is a promising predictor of systemic bacterial infection in children with CKD, with good sensitivity and specificity. This study proposes that serum PCT is a convenient index of infection in CKD children at a cutoff value of 0.5 ng/ml.

Pneumocystis jirovecii pneumonia in patients with end-stage renal disease: a comparison with the general population

BACKGROUND

Data on occurrence and risk factors for pneumocystis pneumonia (PCP) in patients with end-stage renal disease (ESRD) are sparse.

METHODS

This was a nationwide population-based study assessing occurrence and risk factors for PCP among patients with ESRD and population controls over a 21-year period (1/1 1990 to 31/12 2010). Using Danish registry data, first-time diagnoses of PCP were identified.

RESULTS

We identified 13 296 adult patients with ESRD and 244 255 controls, yielding 63 560 and 2 223 660 person-years of follow-up (PYFU), respectively. Fifty-eight first-time diagnoses of PCP were recorded in the ESRD group. Forty-six episodes occurred among renal transplant recipients (RTx) and 12 among haemodialysis patients (HD), yielding incidence rates of 181 (136-242) and 43.1 (24.5-75.9) per 100 000 PYFU. Compared to population controls, we found incidence rate-ratios of 125.9 (78.4-204) among RTx and 29.9 (14.1-59.7) among HD patients. Risk factors for PCP in RTx were age 50-65 years, age > 65 years, diabetes, polycystic kidney disease and hypertensive kidney disease/nephrosclerosis with an IRR of 2.22 (1.14-4.31), 3.12 (1.35-7.21), 3.44 (1.16-10.2), 4.25 (1.55-11.7) and 3.87 (1.49-10.0), respectively, and more than 36 months of dialysis before transplantation with an IRR of 1.99 (1.03-3.84). Among RTx the risk of PCP was highest during the first 6 months post-transplantation and increased from the beginning (IR1990-94 = 111 (46.3-267) per 100 000 PYFU) towards the end of the study period (IR2005-10 = 299 (203-439)).

CONCLUSION

The PCP risk is substantial in RTx within the first 6 months of transplantation, emphasizing the potential benefit of prophylactic treatment in the early post-transplant period. Importantly, we identified subgroups within the RTx group that require more attention.

Description and predictive factors of infection in patients with chronic kidney disease admitted to the critical care unit

OBJECTIVES

To describe the spectrum of infection and multidrug-resistant bacterial colonization, and to identify early predictors of infection in patients with chronic kidney disease (CKD) admitted to the critical care unit (CCU).

METHODS

A 7-month observational prospective single-centre study in a French university hospital.

RESULTS

791 patients were admitted to the CCU, 135 of whom (17%) had severe CKD. Among these, 41 (30%) were infected on admission. Infection was microbiologically documented in 32 patients (78%), of which 7 (22%) were related to Pseudomonas aeruginosa. There was no infection related to extended-spectrum β-lactamase-producing enterobacteriaceae despite a 12% carriage rate on admission. A temperature ≥37.6 °C and a leukocyte count >12.000/mm³ were specific but poorly sensitive of infection (91% and 80%, and 45% and 39%, respectively). Using the threshold of 0.85 ng/ml, procalcitonin was a strong independent predictor of infection on admission (OR 12.8, 95% CI 4.4-37.3). Age (≥60 years) and the cause of CKD were two other predictors.

CONCLUSIONS

Infection accounts for one-third of CCU admissions in CKD patients, with a high prevalence of P. aeruginosa. The usual diagnostic criteria are inaccurate for diagnosing infection in this population. A procalcitonin ≥0.85 ng/ml might be helpful for early identifying CKD patients with infection.