Severe acute kidney injury according to the RIFLE (risk, injury, failure, loss, end stage) criteria affects mortality in lung transplantation

BACKGROUND

The RIFLE criteria (risk, injury, failure, loss, end stage) are new consensus definitions for acute kidney injury (AKI) associated with increased mortality; however, they have not been applied in lung transplantation (LTx). Using the RIFLE criteria, we examined the effect of AKI on outcomes and cost in LTx.

METHODS

We retrospectively reviewed all LTx patients at our institution since the lung allocation score (LAS) system was initiated (May 2005-August 2010). Using the Modification of Diet in Renal Disease formula, we assigned appropriate RIFLE class (R, I, F) comparing baseline creatinine to peak levels in the first 7 days after LTx. Generalized linear models assessed the effect of AKI on in-hospital and 1-year mortality. Hospital charges were used to examine the financial effect of AKI.

RESULTS

During the study, 106 LTx were performed. Excluding patients bridged to LTx with extracorporeal membrane oxygenation, 84 (86%) lived 1 year. Median LAS was 37.1 (interquartile range, 34.1-45.2). RIFLE status was I or F in 39 (36.7%), and 14 (13.2%) required renal replacement therapy (RRT). After adjusting for LAS, RIFLE-F had an increased relative rate (RR) of in-hospital mortality (RR, 4.76, 95% confidence interval [CI], 1.65-13.7, p = 0.004) and 1-year mortality (RR, 3.17, 95% CI 1.55-6.49, p = 0.002). RIFLE-R and I were not associated with higher in-hospital or 1-year mortality. Post-operative RRT was associated with increased in-hospital (RR, 28.2; 95% CI, 6.18-128.1; p < 0.001) and 1-year mortality (RR, 4.97; 95% CI, 1.54-16.0; p < 0.001). AKI patients had higher median hospital charges of $168,146 vs $143,551 for no AKI (p = 0.02).

CONCLUSIONS

This study shows high rates of AKI using the new RIFLE criteria in LTx. RIFLE-F is associated with higher in-hospital and 1-year mortality. Less severe degrees of AKI are not associated with increased mortality. The financial burden associated with AKI is significant.

Society of Thoracic Surgeons Risk Score predicts hospital charges and resource use after aortic valve replacement

OBJECTIVE

The impact of Society of Thoracic Surgeons predicted mortality risk score on resource use has not been previously studied. We hypothesize that increasing Society of Thoracic Surgeons risk scores in patients undergoing aortic valve replacement are associated with greater hospital charges.

METHODS

Clinical and financial data for patients undergoing aortic valve replacement at The Johns Hopkins Hospital over a 10-year period (January 2000 to December 2009) were reviewed. The current Society of Thoracic Surgeons formula (v2.61) for in-hospital mortality was used for all patients. After stratification into risk quartiles, index admission hospital charges were compared across risk strata with rank-sum and Kruskal-Wallis tests. Linear regression and Spearman's coefficient assessed correlation and goodness of fit. Multivariable analysis assessed relative contributions of individual variables on overall charges.

RESULTS

A total of 553 patients underwent aortic valve replacement during the study period. Average predicted mortality was 2.9% (±3.4) and actual mortality was 3.4% for aortic valve replacement. Median charges were greater in the upper quartile of patients undergoing aortic valve replacement (quartiles 1-3, $39,949 [interquartile range, 32,708-51,323] vs quartile 4, $62,301 [interquartile range, 45,952-97,103], P < .01]. On univariate linear regression, there was a positive correlation between Society of Thoracic Surgeons risk score and log-transformed charges (coefficient, 0.06; 95% confidence interval, 0.05-0.07; P < .01). Spearman's correlation R-value was 0.51. This positive correlation persisted in risk-adjusted multivariable linear regression. Each 1% increase in Society of Thoracic Surgeons risk score was associated with an added $3000 in hospital charges.

CONCLUSIONS

This is the first study to show that increasing Society of Thoracic Surgeons risk score predicts greater charges after aortic valve replacement. As competing therapies, such as percutaneous valve replacement, emerge to treat high-risk patients, these results serve as a benchmark to compare resource use.

Appropriate goal level for 25-hydroxyvitamin D in cystic fibrosis

BACKGROUND

Vitamin D deficiency is common in patients with cystic fibrosis (CF), and guidelines recommend 25-hydroxyvitamin D (25OHD) levels ≥ 30 ng/mL. This threshold was selected because serum parathyroid hormone (PTH) rises in healthy individuals when the 25OHD level falls below 30 ng/mL. PTH levels > 50 pg/mL are associated with an increased risk of bone loss. However, the relationship between 25OHD and PTH has not been studied in CF. We sought to determine the appropriate goal 25OHD level in patients with CF by identifying the level below which the risk of PTH > 50 pg/mL begins to increase.

METHODS

Levels of 25OHD and PTH in 216 individuals with CF were collected prospectively. Individuals with 25OHD < 30 ng/mL were treated with vitamin D2, and levels were reevaluated.

RESULTS

Mean 25OHD level was 25.7 ± 12.4 ng/mL, and mean PTH level was 46.7 ± 25.9 pg/mL. In 63% of individuals, 25OHD level was < 30 ng/mL, and in 38.0% it was ≤ 20 ng/mL. Low 25OHD levels were significantly associated with elevated PTH levels, with a mean PTH of 53.1 ± 29.8 pg/mL for 25OHD level 0 to 19 ng/mL; 51.1 ± 30.7 pg/mL for 25OHD level 20 to 29 ng/mL; 38.4 ± 16.4 pg/mL for 25OHD level 30 to 39 ng/mL; and 37.2 ± 16.4 pg/mL for 25OHD level ≥ 40 ng/mL (P = .006). We assessed the sensitivity of different 25OHD thresholds to identify individuals meeting the goal of a PTH level < 50 pg/mL to reduce the risk of bone loss. To obtain 90% sensitivity, a 25OHD level ≥ 35 ng/mL was required. Strikingly, 23% of individuals with 25OHD levels 30 to 34 ng/mL still had a PTH level > 50 pg/mL. This decreased to 14% for 25OHD level ≥ 35 ng/mL.

CONCLUSIONS

Inadequate serum 25OHD levels are common in adults with CF and are associated with elevated PTH levels. Aiming to maintain 25-OHD levels ≥ 35 ng/mL in individuals with CF decreases the risk of having a PTH level associated with secondary hyperparathyroidism and bone loss.

Prevalence and risk factors for unrecognized obstructive lung disease among urban drug users

Background

Obstructive lung disease (OLD) is frequently unrecognized and undertreated. Urban drug users are at higher risk for OLD due to race, behavioral, and socioeconomic characteristics, yet little data exist on prevalence and risk factors associated with unrecognized OLD in this population.

Objective

The objective of this study is to determine the prevalence of unrecognized OLD in an urban population and identify the characteristics associated with lack of physician-diagnosed OLD.

Design

Cross-sectional analysis from the Acquired Immunodeficiency Syndrome Linked to the Intravenous Experience (ALIVE) study, an observational study of current and former injection drug users in Baltimore, Maryland, USA.

Participants

All participants with spirometry-defined airflow obstruction were stratified by the presence or absence of physician diagnosis of OLD.

Main measures

Using cross-sectional demographic, clinical, and spirometric measurements, multivariable regression models were generated to identify factors independently associated with unrecognized OLD.

Key results

Of the 1083 participants evaluated in the ALIVE lung substudy, 176 (16.3%) met spirometric criteria for OLD. Of those, only 88 (50%) had a physician diagnosis of OLD. The prevalence of unrecognized OLD decreased as severity of airflow obstruction increased. Factors independently associated with unrecognized OLD were absence of respiratory symptoms (prevalence ratio [PR], 1.70; 95% confidence interval [CI]: 1.29–2.23; P < 0.01) and less severe dyspnea (PR, 0.83; 95% CI: 0.72–0.96, per point increase in dyspnea scale; P = 0.01). In the subset of human immunodeficiency virus (HIV)–infected participants, the use of antiretroviral therapy (ART) was independently associated with an increased prevalence of unrecognized OLD (PR, 1.93; 95% CI: 1.05–3.56; P = 0.03).

Conclusions

In a cohort of current and former urban drug users, OLD is substantially underrecognized and associated with lack of respiratory symptoms. Relying on the presence of respiratory symptoms as a trigger to perform spirometry may result in a substantial underdiagnosis of OLD in this population. HIV-infected individuals receiving ART are a population particularly vulnerable to unrecognized OLD.

Tobacco use and nicotine dependence among HIV-infected and uninfected injection drug users

INTRODUCTION

Urban U.S. populations are burdened by intersecting epidemics of HIV infection, injection drug use, and cigarette smoking. Given the substantial morbidity attributable to tobacco in these populations, we characterized smoking behaviors, nicotine addiction, and tobacco exposure among HIV-infected and HIV-uninfected injection drug users (IDUs) in Baltimore, Maryland.

METHODS

Smoking behaviors among participants in the ALIVE Study were assessed using interviewer-administered questionnaires. Smoking history and nicotine dependence (Fagerstrom Index scores) were compared by HIV and drug injecting status. Serum cotinine (a nicotine metabolite) was measured for a sample of participants by enzyme immunoassay.

RESULTS

Among 1052 participants (29.7% HIV-infected, 39.8% active injectors), 85.2% were current smokers and 9.3% were former smokers. Smoking prevalence, age at smoking initiation, and cumulative tobacco exposure were similar by HIV status. Median Fagerstrom scores of 4 for HIV-infected and HIV-uninfected smokers indicated moderate nicotine dependence. Daily cigarette consumption was identical by HIV status (median 10 cigarettes), although HIV-infected participants were less likely to smoke 1+ pack daily compared to HIV-uninfected participants (18.0% vs. 26.9%, p=0.001). Compared to former injectors, active injectors had higher smoking prevalence (90.5% vs. 81.7%, p=0.0001), greater daily cigarette consumption (30.7% vs. 19.6% smoked 1+ pack daily, p=0.0001), and slightly higher Fagerstrom scores (median 5 vs. 4). Cotinine levels paralleled self-reported cigarette consumption.

DISCUSSION

Tobacco use is extremely common among inner-city IDUs. Smoking behavior and nicotine dependence did not materially differ by HIV status but were associated with active drug injection. Cessation efforts should target the dual dependence of cigarettes and drugs experienced among this population.

Low potassium dextran is superior to University of Wisconsin solution in high-risk lung transplant recipients

BACKGROUND

The ideal solution for recovery of donor lungs remains unknown. Low potassium dextran (LPD) solution is most common, but University of Wisconsin (UW) solution is also used. The United Network for Organ Sharing (UNOS) database allows assessment of preservation solutions in a large cohort of lung transplant (LTx) patients.

METHODS

We retrospectively reviewed the UNOS data set for adult primary LTx patients (2005-2008) whose donor lungs were recovered with UW or LPD solution. Patients were stratified by UW vs LPD, and secondarily grouped by quartiles of the lung allocation score (LAS) to examine high-risk recipients. Kaplan-Meier (KM) short-term mortality (30 days, 90 days, 1 year) and rejection in the first year were examined for intervals with adequate follow-up. Cox proportional hazard regression using 11 variables examined all cause 1-year mortality.

RESULTS

Of 4,455 patients, 4,161 (93.4%) received LPD lungs and 294 (6.6%) received UW lungs, and 1,105 patients (24.8%) died during the study. There was no mortality difference based on flush solution with all patients examined together. However, patients in the upper 2 LAS quartiles (Q3: 37.8-45.4, Q4: > 45.4) receiving LPD lungs had greater 1-year survival of 81.5% vs 73.5% (p = 0.02). On multivariable analysis, flush with UW solution resulted in an increased risk of 1-year mortality (hazard ratio, 1.77. 95% confidence interval, 1.21-2.58; p = 0.003) vs LPD. Preservation solution did not affect rejection rates in the year after LTx. KM modeling demonstrated the effect of flush solution on survival (p = 0.02).

CONCLUSIONS

This study is the largest modern cohort to evaluate the effect of donor lung flush solutions on survival in adult LTx. UW solution increases the risk of 1-year mortality in high-risk LTx recipients.

HIV and COPD: impact of risk behaviors and diseases on quality of life

PURPOSE

Smoking worsens quality of life among HIV-infected individuals, but it remains unclear if this association is related simply to smoking or to chronic obstructive pulmonary disease (COPD), the end-organ disease caused by smoking.

METHODS

Using cross-sectional data from the AIDS Linked to the Intravenous Experience study, we determined the independent effects of smoking, HIV and COPD assessed using the Medical Outcome Studies-HIV questionnaire.

RESULTS

Of 973 participants, 287 (29.5%) were HIV infected and 151 (15.5%) had spirometry-defined obstruction. Eight hundred and thirty-four (85.7%) were current smokers with 23.3 mean pack-years history. HIV infection was independently associated with reduced physical and mental health. COPD was associated with a trend toward worse physical health (-1.48 units; 95%CI -3.33 to 0.38; p = 0.12) and was independently associated with worse mental health (-2.43 units; 95%CI -4.22 to -0.64; p < 0.01). After accounting for COPD and other covariates, smoking was not associated with changes in physical or mental health.

CONCLUSIONS

The presence of COPD, rather than smoking, is associated with worse quality of life independent of HIV infection. Diagnosis and management of COPD in former or current smokers with or at risk for HIV may further improve quality of life.

Association between respiratory tract methicillin-resistant Staphylococcus aureus and survival in cystic fibrosis

CONTEXT

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the respiratory tract of individuals with cystic fibrosis (CF) has increased dramatically; however, its impact on outcomes in CF is unclear. Because the time between infection with bacteria in CF and death can be decades, observational studies with long periods of follow-up are well suited to address the current gap in knowledge.

OBJECTIVE

To determine whether isolation of MRSA from the respiratory tract of CF patients is associated with worse survival compared with patients who never have a culture positive for MRSA.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study of 19,833 CF patients aged 6 to 45 years seen at centers accredited by the Cystic Fibrosis Foundation in the United States. Patients entered between January 1996 and December 2006 and were followed up through December 2008. Cox regression models with time-varying covariates were used to compare survival between CF patients with and without respiratory tract MRSA.

MAIN OUTCOME MEASURE

Time from age at entry until age at death from any cause.

RESULTS

In 137,819 patient-years of observation (median, 7.3 years/patient), 2537 CF patients died and 5759 patients had MRSA detected. The mortality rate was 18.3 deaths (95% confidence interval [CI], 17.5-19.1) per 1000 patient-years in patients without MRSA and 27.7 deaths (95% CI, 25.3-30.4) per 1000 patient-years in those with MRSA. Among those with MRSA, the attributable risk percentage of death associated with MRSA was 34.0% (95% CI, 26.7%-40.4%). The unadjusted hazard ratio associated with MRSA was 1.47 (95% CI, 1.32-1.62). After adjustment for time-varying covariates associated with severity of illness, MRSA remained associated with a higher risk of death (1.27; 95% CI, 1.11-1.45).

CONCLUSION

Detection of MRSA in the respiratory tract of CF patients was associated with worse survival.

Cross sectional analysis of respiratory symptoms in an injection drug user cohort: the impact of obstructive lung disease and HIV

Background

Injection drug use is associated with an increased risk of human immunodeficiency virus (HIV) infection and with obstructive lung diseases (OLD). Understanding how HIV and OLD may impact respiratory symptoms among injection drug users (IDUs) is important to adequately care for this high-risk population. We characterized the independent and joint effects of HIV and OLD on respiratory symptoms of a cohort of inner-city IDUs.

Methods

Demographics, risk behavior and spirometric measurements were collected from a cross-sectional analysis of the Acquired Immunodeficiency Syndrome Link to the IntraVenous Experience study, an observational cohort of IDUs followed in Baltimore, MD since 1988. Participants completed a modified American Thoracic Society respiratory questionnaire and the Medical Research Council (MRC) dyspnea score to assess respiratory symptoms of cough, phlegm, wheezing and dyspnea.

Results

Of 974 participants, 835 (86%) were current smokers and 288 (29.6%) were HIV-infected. The prevalence of OLD (FEV1/FVC ≤ 0.70) was 15.5%, and did not differ by HIV status. OLD, but not HIV, was associated with increased frequency of reported respiratory symptoms. There was a combined effect of OLD and HIV on worsening of MRC scores. OLD and HIV were independently associated with an increased odds of reporting an MRC ≥ 2 (OR 1.83 [95%CI 1.23-2.73] and 1.50 [95%CI 1.08-2.09], respectively). COPD, but not HIV, was independently associated with reporting an MRC ≥ 3 (OR 2.25 [95%CI 1.43-3.54] and 1.29 [95%CI 0.87-1.91], respectively).

Conclusions

While HIV does not worsen cough, phlegm or wheezing, HIV significantly increases moderate but not severe dyspnea in individuals of similar OLD status. Incorporating the MRC score into routine evaluation of IDUs at risk for OLD and HIV provides better assessment than cough, phlegm and wheezing alone.

Factors indicative of long-term survival after lung transplantation: a review of 836 10-year survivors

INTRODUCTION

Despite 20 years of lung transplantation (LTx), factors influencing long-term survival remain largely unknown. The United Network for Organ Sharing (UNOS) data set provides an opportunity to examine long-term LTx survivors.

METHODS

We conducted a case-control study embedded within the prospectively collected UNOS LTx cohort to identify 836 adults from 1987 to 1997 who survived >or=10 years after first LTx. LTx patients within the same era and surviving 1 to 5 years served as controls. Multivariable logistic regression with incorporation of spline terms evaluated the odds of being a 10-year survivor. Two separate models were constructed. Model A incorporated pre-operative, operative, and donor-specific factors. Model B incorporated the factors used in Model A with post-operative covariates. Additional outcomes evaluated included hospitalizations for infection, rejection, and bronchiolitis obliterans.

RESULTS

Of 4,818 LTx patients from 1987 to 1997, 836 (17.3%) survived >or=10 years with a mean follow-up of 148.8 +/- 21.6 months. Mean follow-up for 1,657 controls was 34.0 +/- 13.9 months. The distribution of 10-year survivors by disease was cystic fibrosis, 170 (20%); chronic obstructive pulmonary disease, 254 (30%); and idiopathic pulmonary fibrosis, 92 (11%). On multivariable logistic regression, significant factors influencing 10-year survival included age <or=35 years (odds ratio [OR] 1.07, 95% confidence interval [CI], 1.03-1.11; p = 0.01), bilateral LTx (OR. 1.71; 95% CI, 1.25-2.34; p = 0.001), and hospitalizations for infections (OR, 1.40; 95% CI, 1.27-1.54; p < 0.001) and for rejection (OR, 0.55; 95% CI, 0.48-0.65; p < 0.001).

CONCLUSIONS

Examination of a cohort of long-term LTx survivors in the UNOS data set indicates that bilateral LTx and fewer hospitalizations for rejection may portend improved long-term survival after LTx.

Survival after single versus bilateral lung transplantation for high-risk patients with pulmonary fibrosis

BACKGROUND

Whether single lung transplantation (SLT) or bilateral lung transplantation (BLT) is optimal for patients with severe idiopathic pulmonary fibrosis (IPF) is unknown. We examine a large multi-institutional cohort of high-risk IPF patients to address this question.

METHODS

We retrospectively reviewed United Network for Organ Sharing data to identify 1,256 lung transplant (LTx) recipients with IPF between 2005 and 2007. Risk of 30-day, 90-day, and 1-year mortality for SLT versus BLT was examined across levels of the lung allocation score (LAS [both continuous with incorporation of interaction terms and categorized by LAS quartiles]). Multivariable analysis was conducted through Cox proportional hazards regression.

RESULTS

Lung allocation score quartiles were as follows: quartile 1, 29.8 to 37.8, n = 315; quartile 2, 37.9 to 42.4, n = 313; quartile 3, 42.5 to 51.9, n = 314; and quartile 4, 52.0 to 94.1, n = 314. Overall, 21.1% more patients received BLT in the highest LAS quartile (59.5%) than in the lowest LAS quartile (38.4%, p < 0.05). In patients at highest risk, BLT was associated with a 14.4% decrease in mortality at 1 year after LTx. This survival benefit was confirmed on univariate analysis (hazard ratio 1.90 [95% confidence interval: 1.16 to 3.13], p = 0.01) and multivariable analysis (hazard ratio 2.09 [95% confidence interval: 1.07 to 4.10], p = 0.03) as well as in sensitivity analyses incorporating pulmonary hypertension and maximizing follow-up. There were no differences in the risk of death with SLT at 30 or 90 days after LTx in any quartile on unadjusted or multivariable adjusted analysis.

CONCLUSIONS

We provide an initial examination of survival by procedure type and LAS score for LTx recipients with IPF. Bilateral LTx appears to offer advantages over SLT for high-risk patients.

Impact of U.S. Lung Allocation Score on survival after lung transplantation

BACKGROUND

The Lung Allocation Score (LAS) dramatically changed organ allocation in lung transplantation. The impact of this change on patient outcomes is unknown. The purpose of the study was to examine early mortality after lung transplantation under the LAS system.

METHODS

All patients undergoing first-time lung transplantation during the period from May 1, 2005 through April 30, 2008 were included in the study. The cohort was divided into quintiles by LAS. A high-risk group (LAS >46) was comprised of the highest quintile, Quintile 5, and a low-risk group (LAS < or =46) included the lower quintiles, Quintiles 1 through 4. A time-to-event analysis was performed for risk of death after transplantation using Kaplan-Meier survival and Cox proportional hazards models.

RESULTS

There were 4,346 patients who underwent lung transplantation during the study period. Patients in the high-risk group (LAS >46) were more likely to have idiopathic pulmonary fibrosis (IPF; 52.9% vs 23.8%, p < 0.001) and diabetes (25.8% vs 16.8%, p < 0.001) and to require mechanical ventilatory support (15.4% vs 2.2%, p < 0.001) at the time of transplant as compared with patients in the low-risk group. One-year survival using the Kaplan-Meier product limit estimator was significantly worse in the high-risk group (75% vs 83%, p < 0.001 by log-rank test). Patients in the high-risk group were also found to have increased risk of death (hazard ratio 1.46, 95% confidence interval 1.24 to 1.73) compared with the low-risk group.

CONCLUSIONS

Overall 1-year survival under the new LAS system appears to be similar to that in historic reports. However, risk of death was significantly increased among patients with LAS >46.

The impact of center volume on survival in lung transplantation: an analysis of more than 10,000 cases

BACKGROUND

Whether center volume influences outcomes in lung transplantation is unknown. We reviewed United Network for Organ Sharing data to examine the effect of center volume on short-term mortality.

METHODS

We reviewed United Network for Organ Sharing data (1998 through 2007) to identify 10,496 first-time adult lung transplantation recipients at 79 centers. Centers were stratified by quartiles of mean annual volume. Risk of 30-day mortality and 1- and 5-year mortality (censored for 30-day death) were assessed by multivariable Cox proportional hazards regression.

RESULTS

Mean center volume ranged from less than 1 to 58.2 (median, 9.4 cases/year; volume quartiles: 0 to 2.1, 2.2 to 9.4, 9.5 to 19.9, and 20 to 58.2 cases). Each 1 case/year decrease led to a 2% increase in 30-day mortality (hazard ratio, 1.02; 95% confidence interval, 1.01 to 1.02; p < 0.001). Centers of lowest quartile (performing <or=2.1 lung transplantations/year) had a 30-day cumulative mortality of 9.6% or 89% increase in the risk of death (hazard ratio, 1.89; 95% confidence interval, 1.01 to 3.44; p = 0.05) compared with the highest quartile centers despite fewer idiopathic pulmonary fibrosis patients (15.6% versus 25.8%; p < 0.001) and younger age (40.9 versus 51.5 years; p < 0.001). Low-volume centers had double the risk of 30-day censored 1-year mortality (hazard ratio, 1.95; 95% confidence interval, 1.30 to 2.92; p = 0.001). High-volume centers (>or=20 lung transplantations/year) had the lowest 30-day mortality (4.1%).

CONCLUSIONS

We provide an initial examination of the relationship of volume and lung allocation score to outcomes for lung transplantation. Low center volume is associated with increased short-term and cumulative mortality despite fewer idiopathic pulmonary fibrosis patients and younger patients.

Lung transplantation in older patients with cystic fibrosis: analysis of UNOS data

BACKGROUND

The lifespan for patients with cystic fibrosis (CF) is increasing. As a result, greater numbers of older CF patients are presenting for lung transplantation (LTx). The UNOS database provides an opportunity to examine outcomes for this population.

METHODS

We retrospectively reviewed UNOS data to identify 1,637 first-time LTx recipients with the indication of CF between 1999 and 2007. Patients were stratified by quartile age. Our primary end-point was all-cause mortality. Post-transplant survival was compared using Cox proportional hazards regression.

RESULTS

Of the patients who met the inclusion criteria, the distribution by age quartile was as follows: Quartile 1 (Q1), age 7 to 20 years, N = 408; Q2, 21 to 27, N = 470; Q3, 28 to 34, N = 365; and Q4, >or=35, N = 394. Patients in the lowest quartile had the lowest 5-year cumulative survival (43%); 19% lower than for patients in Quartile 4 (age >or=35, cumulative survival = 62%; p < 0.001). On multivariable analysis, patients in Q3 and Q4 had a 38% and 32% reduction in cumulative hazard for death, respectively (reference Q1, age 7 to 20) (hazards ratios: Q3, 0.62 [0.46 to 0.85], p < 0.001; Q4, 0.68 [0.5 to 0.93], p = 0.02). Thirty-day and 1-year cumulative survival were not different among the four quartiles (30-day survival: Q1, 96.4%; Q2, 96.2%; Q3, 96.2%; and Q4, 95.5% [p = 0.94]; 1-year survival: Q1, 83.7%; Q2, 83.1%; Q3, 85.4%; and Q4, 83.4% [p 0.88]). Increasing age was associated with decreases in early post-operative infections, reduction in the cumulative hazard of developing bronchiolitis obliterans (BO) syndrome, and decreases in hospitalizations and treatment for rejection.

CONCLUSIONS

The UNOS database has provided a large series examining survival after LTx in older CF patients. LTx is safe in this group and older age may be protective against infection, rejection and BO syndrome.

Patients with mutations in Gsalpha have reduced activation of a downstream target in epithelial tissues due to haploinsufficiency

CONTEXT

Patients with Albright hereditary osteodystrophy (AHO) have defects in stimulatory G protein signaling due to loss of function mutations in GNAS. The mechanism by which these mutations lead to the AHO phenotype has been difficult to establish due to the inaccessibility of the affected tissues.

OBJECTIVE

The objective of the study was to gain insight into the downstream consequences of abnormal stimulatory G protein signaling in human epithelial tissues.

PATIENTS AND DESIGN

We assessed transcription of GNAS and Gsalpha-stimulated activation of the cystic fibrosis transmembrane conductance regulator (CFTR) in AHO patients, compared with normal controls and patients with cystic fibrosis.

MAIN OUTCOME MEASURES

Relative expression of Gsalpha transcripts from each parental GNAS allele and cAMP measurements from nasal epithelial cells were compared among normal controls and AHO patients. In vivo measurements of CFTR function, pulmonary function, and pancreatic function were assessed in AHO patients.

RESULTS

GNAS was expressed equally from each allele in normals and two of five AHO patients. cAMP generation was significantly reduced in nasal respiratory epithelial cells from AHO patients, compared with normal controls (0.4 vs. 0.6, P = 0.0008). Activation of CFTR in vivo in nasal (P = 0.0065) and sweat gland epithelia (P = 0.01) of AHO patients was significantly reduced from normal. In three patients, the reduction in activity was comparable with patients with cystic fibrosis due to mutations in CFTR. Yet no AHO patients had pulmonary or pancreatic disease consistent with cystic fibrosis.

CONCLUSIONS

In humans, haploinsufficiency of GNAS causes a significant reduction in the activation of the downstream target, CFTR, in vivo.

Incidence and risk factors for multiple antibiotic-resistant Pseudomonas aeruginosa in cystic fibrosis

BACKGROUND

Infection with multiple antibiotic-resistant Pseudomonas aeruginosa (MARPA) in individuals with cystic fibrosis (CF) has caused much concern among caregivers, yet little is known about the risks associated with acquiring resistance. The main objective of the study was to estimate the incidence and identify risk factors for the acquisition of MARPA among individuals with CF.

METHODS

Five-year cohort study of individuals followed in the Cystic Fibrosis Foundation Registry from 1998 through 2002.

RESULTS

Demographics, anthropometrics, spirometry, respiratory culture results, comorbidities, antibiotic usage, and hospitalizations were collected. Of the 4,293 patients with P aeruginosa infection during the study period, MARPA developed in 341. The overall incidence of MARPA was 1.8%/yr. Independent risk factors for MARPA included CF-related diabetes mellitus (hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.11 to 2.43), long-term inhaled tobramycin usage (HR, 2.08; 95% CI, 1.56 to 2.77), and care at a CF center with a baseline MARPA prevalence in the top quartile (HR, 2.00; 95% CI, 1.31 to 3.04). Frequent courses of IV antibiotics and repeated hospitalizations were also found to independently increase the risk for MARPA.

CONCLUSIONS

Infection with MARPA is common among patients with CF. Diabetes, long-term inhaled tobramycin usage, and frequent acute pulmonary exacerbations requiring hospitalization or IV antibiotics increase the risk for MARPA. Receiving CF care at a center with a high prevalence of resistant Pseudomonas also increases the risk for MARPA in patients with CF. Further study is needed to investigate the mechanisms of acquiring resistant strains and the clinical impact of MARPA on CF outcomes.

Respiratory epithelial gene expression in patients with mild and severe cystic fibrosis lung disease

Despite having identical cystic fibrosis transmembrane conductance regulator genotypes, individuals with DeltaF508 homozygous cystic fibrosis (CF) demonstrate significant variability in severity of pulmonary disease. This investigation used high-density oligonucleotide microarray analysis of nasal respiratory epithelium to investigate the molecular basis of phenotypic differences in CF by (1) identifying differences in gene expression between DeltaF508 homozygotes in the most severe 20th percentile of lung disease by forced expiratory volume in 1 s and those in the most mild 20th percentile of lung disease and (2) identifying differences in gene expression between DeltaF508 homozygotes and age-matched non-CF control subjects. Microarray results from 23 participants (12 CF, 11 non-CF) met the strict quality control guidelines and were used for final data analysis. A total of 652 of the 11,867 genes identified as present in 75% of the samples were significantly differentially expressed in one of the three disease phenotypes: 30 in non-CF, 53 in mild CF, and 569 in severe CF. An analysis of genes differentially expressed by severity of CF lung disease demonstrated significant upregulation in severe CF of genes involved in protein ubiquination (P < 0.04), mitochondrial oxidoreductase activity (P < 0.01), and lipid metabolism (P < 0.03). Analysis of genes with decreased expression in patients with CF compared with control subjects demonstrated significant downregulation of genes involved in airway defense (P < 0.047) and protein metabolism (P < 0.048). This study suggests that differences in CF lung phenotype are associated with differences in expression of genes involving airway defense, protein ubiquination, and mitochondrial oxidoreductase activity and identifies specific new candidate modifiers of the CF phenotype.