Association between chronic obstructive pulmonary disease and chronic kidney disease in vascular surgery patients

Kidney function and obstructive lung disease: a bidirectional Mendelian randomisation study

BACKGROUND

Additional study is warranted to investigate the causal effects between kidney function and obstructive lung disease.

METHODS

This study was a bidirectional two-sample Mendelian randomisation (MR) analysis. The CKDGen genome-wide association study (GWAS) meta-analysis for estimated glomerular filtration rate (eGFR) including individuals of European ancestry (N=567 460) provided the genetic instrument for kidney function and outcome summary statistics. A GWAS for FEV1/FVC including individuals of European ancestry from the UK Biobank (N=321 047) provided the genetic instrument for FEV1/FVC and outcome data. A polygenic score (PGS) analysis was performed to test the causal estimates from kidney function to binary obstructive lung disease outcomes, including chronic obstructive pulmonary disease (COPD), asthma, and FEV1/FVC<70%, and to perform non-linear MR with individual-level UK Biobank data.

RESULTS

The causal estimates by summary-level MR indicated that genetically predicted increased kidney function was significantly associated with increased FEV1/FVC Z scores [10% increase in eGFR, beta 0.055 (0.024, 0.086)]. The PGS for increased eGFR showed a significant association with a reduced risk of FEV1/FVC<70% [OR 0.93 (0.87, 0.99)], COPD [OR 0.93 (0.87, 0.99)] and late-onset (≥50 years old) asthma [OR 0.93 (0.88, 0.99)]. The non-linear MR demonstrated that the causal effect from eGFR to FEV1/FVC was apparent in eGFR ranges lower than 60 mL/min/1.73 m². On the other hand, genetically predicted FEV1/FVC showed nonsignificant causal estimates of eGFR change [beta 0.568% (-0.458, 1.605%)].

CONCLUSION

This study supports kidney function impairment would be a causative factor for obstructive lung disease.

Management of the COPD Patient with Comorbidities: An Experts Recommendation Document

Background

Chronic obstructive pulmonary disease (COPD) is associated with multiple comorbidities, which impact negatively on patients and are often underdiagnosed, thus lacking a proper management due to the absence of clear guidelines.

Purpose

To elaborate expert recommendations aimed to help healthcare professionals to provide the right care for treating COPD patients with comorbidities.

Methods

A modified RAND-UCLA appropriateness method consisting of nominal groups to draw up consensus recommendations (6 Spanish experts) and 2-Delphi rounds to validate them (23 Spanish experts) was performed.

Results

A panel of Spanish internal medicine experts reached consensus on 73 recommendations and 81 conclusions on the clinical consequences of the presence of comorbidities. In general, the experts reached consensus on the issues raised with regard to cardiovascular comorbidity and metabolic disorders. Consensus was reached on the use of selective serotonin reuptake inhibitors in cases of depression and the usefulness of referring patients with anxiety to respiratory rehabilitation programmes. The results also showed consensus on the usefulness of investigating the quality of sleep, the treatment of pain with opioids and the evaluation of osteoporosis by lateral chest radiography.

Conclusion

This study provides conclusions and recommendations that are intended to improve the management of the complexity of patients with COPD and important comorbidities, usually excluded from clinical trials.

Association among chronic kidney disease, airflow limitation, and mortality in a community-based population: The Yamagata (Takahata) study

Chronic kidney disease (CKD) and chronic obstructive pulmonary disease (COPD) are known risk factors for mortality. In this study, we examined the overlap of CKD and airflow limitation (AFL) that characterises COPD and its effect on 10-year mortality in a community-based population. This study included 1,233 health check-up participants (mean age, 63.7 years; 46.7% men). We defined serum creatinine-based CKD (CKDcr) and serum cystatin C-based CKD (CKDcys) as glomerular filtration rate <60 mL/min/1.73 m², estimated using serum creatinine or cystatin C, and/or dipstick proteinuria ≥1+. AFL was defined as forced expiratory volume in 1 s to forced vital capacity ratio <70% on spirometry. Compared with subjects without AFL, those with AFL showed a significantly higher prevalence of CKDcys but not of CKDcr. Cox proportional hazard analysis adjusted for confounders showed that the hazard ratio (95% confidence interval) for all-cause mortality was 1.45 (0.77–2.63) in subjects with CKDcys alone, 1.29 (0.60–2.54) in those with AFL alone, and 2.94 (1.33–6.12) in those with both CKDcys and AFL, with subjects without both AFL and CKD as the reference. This study showed that AFL and CKDcys are strongly associated and that their overlap is a significant risk factor for mortality in community-based populations.

Association of urine mitochondrial DNA with clinical measures of COPD in the SPIROMICS cohort

BACKGROUNDMitochondrial dysfunction, a proposed mechanism of chronic obstructive pulmonary disease (COPD) pathogenesis, is associated with the leakage of mitochondrial DNA (mtDNA), which may be detected extracellularly in various bodily fluids. Despite evidence for the increased prevalence of chronic kidney disease in COPD subjects and for mitochondrial dysfunction in the kidneys of murine COPD models, whether urine mtDNA (u-mtDNA) associates with measures of disease severity in COPD is unknown.METHODSCell-free u-mtDNA, defined as copy number of mitochondrially encoded NADH dehydrogenase-1 (MTND1) gene, was measured by quantitative PCR and normalized to urine creatinine in cell-free urine samples from participants in the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) cohort. Urine albumin/creatinine ratios (UACR) were measured in the same samples. Associations between u-mtDNA, UACR, and clinical disease parameters - including FEV1 % predicted, clinical measures of exercise tolerance, respiratory symptom burden, and chest CT measures of lung structure - were examined.RESULTSU-mtDNA and UACR levels were measured in never smokers (n = 64), smokers without airflow obstruction (n = 109), participants with mild/moderate COPD (n = 142), and participants with severe COPD (n = 168). U-mtDNA was associated with increased respiratory symptom burden, especially among smokers without COPD. Significant sex differences in u-mtDNA levels were observed, with females having higher u-mtDNA levels across all study subgroups. U-mtDNA associated with worse spirometry and CT emphysema in males only and with worse respiratory symptoms in females only. Similar associations were not found with UACR.CONCLUSIONU-mtDNA levels may help to identify distinct clinical phenotypes and underlying pathobiological differences in males versus females with COPD.TRIAL REGISTRATIONThis study has been registered at ClinicalTrials.gov ( NCT01969344).FUNDINGUS NIH, National Heart, Lung and Blood Institute, supplemented by contributions made through the Foundation for the NIH and the COPD Foundation from AstraZeneca/MedImmune, Bayer, Bellerophon Therapeutics, Boehringer-Ingelheim Pharmaceuticals Inc., Chiesi Farmaceutici S.p.A., Forest Research Institute Inc., GlaxoSmithKline, Grifols Therapeutics Inc., Ikaria Inc., Novartis Pharmaceuticals Corporation, Nycomed GmbH, ProterixBio, Regeneron Pharmaceuticals Inc., Sanofi, Sunovion, Takeda Pharmaceutical Company, and Theravance Biopharma and Mylan.

Major comorbidities lead to the risk of adverse cardiovascular events in chronic obstructive pulmonary disease patients using inhaled long-acting bronchodilators: a case-control study

Background

While inhaled bronchodilators reduce symptoms and acute exacerbations of chronic obstructive pulmonary disease (COPD), their use is associated with increased cardiovascular events in some studies. This study investigates the risk of adverse events associated with the use of inhaled bronchodilators in COPD patients with multimorbidity.

Methods

A case-control study was conducted between January 2015 and December 2017, and patients with spirometry-confirmed diagnosis of COPD (N = 1565) using inhaled long-acting bronchodilators were enrolled. Medical records were reviewed and clinical data, including age, gender, smoking status, major comorbidities, lung function stage, history of exacerbations, bronchodilator regimens, and treatment duration were analyzed. Major adverse cardiovascular events occurring during long-acting bronchodilator use were recorded.

Results

The most common comorbidities were cardiovascular disease (CVD) (53.6%) and chronic kidney disease (CKD) (25.8%). We observed that CVD (odds ratio [OR], 5.77), CKD (OR, 2.02) and history of frequent exacerbations (OR, 2.37) were independent risk factors for cardiovascular events, regardless of the type of bronchodilators use. Moreover, COPD patients with both CKD and CVD had higher risk (6.32-fold) of adverse cardiovascular effects than those with neither comorbidity. Eighty-seven of 1565 (5.56%) COPD patients died during this study period. Of them, 21.8% (19/87) were cardiovascular-related and 73.6% (64/87) patients were respiratory-related mortality. Among COPD patients using long-acting bronchodilators, CKD was the only risk factor to predict cardiovascular events and cardiovascular-related mortality (OR, 4.87; 95% confidence interval [CI], 1.75–13.55].

Conclusions

COPD patients had higher risk of cardiovascular events were associated with their CVD and/or CKD comorbidities and history of frequent exacerbations, rather than associated with their use of inhaled bronchodilators.

Consequences of chronic kidney disease in chronic obstructive pulmonary disease

Background

The combination of chronic obstructive pulmonary disease (COPD) and chronic kidney disease (CKD) is associated with a higher prevalence of comorbidities and increased mortality. The impact of kidney function on patient-centered outcomes in COPD has not been evaluated.

Methods

Patients from the German COPD and Systemic Consequences - Comorbidities Network (COSYCONET) cohort COPD were analysed. CKD was diagnosed if the estimated glomerular filtration rate (eGFR) measurements were < 60 mL/min/1.73m² at study inclusion and six month later. The effect of CKD, on comorbidities, symptoms [modified British Medical Research Council dyspnoea scale], physical capacity [six-minute walk test, and timed up and go] and St George’s Respiratory Questionnaire were analysed. Restricted cubic spline models were used to evaluate a nonlinear relationship between eGFR with patient-centered outcomes, cox survival analysis was applied to evaluate mortality.

Results

2274 patients were analysed, with CKD diagnosed in 161 (7.1%). Spline models adjusted for age, gender, BMI, FEV₁ and cardiovascular comorbidities revealed independent associations between eGFR with modified British Medical Research Council dyspnoea scale, St George’s Respiratory Questionnaire, (p < 0.001 and p = 0.011), six-minute walk test (p = 0.015) and timed up and go (p < 0.001). CKD was associated with increased mortality, independently from for other cardiovascular comorbidities (hazard ratio 2.3; p < 0.001).

Conclusion

These data show that CKD is a relevant comorbidity in COPD patients which impacts on patient-centered outcomes and mortality.

Trial registration

NCT01245933

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1107-x) contains supplementary material, which is available to authorized users.

When kidneys and lungs suffer together

A significant interaction between kidneys and lungs has been shown in physiological and pathological conditions. The two organs can both be targets of the same systemic disease (eg., some vasculitides). Moreover, loss of normal function of either of them can induce direct and indirect dysregulation of the other one. Subjects suffering from COPD may have systemic inflammation, hypoxemia, endothelial dysfunction, increased sympathetic activation and increased aortic stiffness. As well as the exposure to nicotine, all the foresaid factors can induce a microvascular damage, albuminuria, and a worsening of renal function. Renal failure in COPD can be unrecognized since elderly and frail patients may have normal serum creatinine concentration. Lungs and kidneys participate in maintaining the acid-base balance. Compensatory role of the lungs rapidly expresses through an increase or reduction of ventilation. Renal compensation usually requires a few days as it is achieved through changes in bicarbonate reabsorption. Chronic kidney disease and end-stage renal diseases increase the risk of pneumonia. Vaccination against Streptococcus pneumonia and seasonal influenza is recommended for these patients. Vaccines against the last very virulent H1N1 influenza A strain are also available and effective. Acute lung injury and acute kidney injury are frequent complications in critical illnesses, associated with high morbidity and mortality. The concomitant failure of kidneys and lungs implies a multidisciplinary approach, both in terms of diagnostic processes and therapeutic management.

Beclin-1 regulates cigarette smoke-induced kidney injury in a murine model of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), associated with cigarette smoke-induced (CS-induced) emphysema, contributes significantly to the global health care burden of disease. Although chronic kidney disease (CKD) may occur in patients with COPD, the relationship between COPD and CKD remains unclear. Using a murine model of experimental COPD, we show that chronic CS exposure resulted in marked kidney injury and fibrosis, as evidenced by histological and ultrastructural changes, altered macrophage subpopulations, and expression of tissue injury, fibrosis, and oxidative stress markers. CS induced mitochondrial dysfunction, and increased autophagic flux in kidney tissues and in kidney tubular epithelial (HK-2) cells, as determined by LC3B turnover assays. Mice heterozygous for Beclin-1 (Becn1+/-) were protected from the development of kidney tissue injury and renal fibrosis in response to CS exposure, and displayed impaired basal and inducible mitochondrial turnover by mitophagy. Interestingly, CS caused a reduction of Beclin-1 expression in mouse kidneys and kidney tubular epithelial cells, attributed to increased autophagy-dependent turnover of Beclin-1. These results suggest that Beclin-1 is required for CS-induced kidney injury and that reduced levels of Beclin-1 may confer renoprotection. These results identify the kidney as a target for CS-induced injury in COPD and the Beclin-1-dependent autophagy pathway as a potential therapeutic target in CKD.

The association between COPD and outcomes of patients with advanced chronic kidney disease

Objective

The aim of this study was to investigate the impact of COPD on the outcomes of patients with advanced chronic kidney disease (CKD).

Patients and methods

All patients with advanced CKD from 2000 to 2010 were identified from the Taiwanese National Health Insurance Research Database. Associations between COPD and the risk of long-term dialysis and all-cause mortality were assessed.

Results

A total of 33,399 advanced CKD patients were enrolled, of whom 31,536 did not have COPD (non-COPD group) and 1,863 had COPD (COPD group). The incidence of end-stage renal disease (ESRD) was higher for those with COPD than those without COPD (744.2 per 1,000 person-years vs 724.6 per 1,000 person-years, adjusted HR [aHR] 1.04; 95% CI 0.96–1.12). The cumulative incidence rates of ESRD were similar between the COPD and non-COPD groups (log-rank test, P=0.356). Overall, the patients with COPD had a higher risk of death than those without COPD (151.7 per 1,000 person-years vs 125.5 per 1,000 person-years, aHR 1.22; 95% CI 1.11–1.33). The cumulative mortality rate was higher in the COPD group than in the non-COPD group (log-rank test, P<0.001).

Conclusion

COPD increased the risk of mortality among the advanced CKD patients in this study, especially the elderly and male patients. In contrast, COPD did not increase the risk of ESRD among the advanced CKD patients.

Severity of acidosis affects long-term survival in COPD patients with hypoxemia after intensive care unit discharge

Background

Patients admitted to the intensive care unit (ICU) with acute respiratory failure (ARF) due to COPD have high mortality and morbidity. Acidosis has several harmful effects on hemodynamics and metabolism, and the current knowledge regarding the relationship between respiratory acidosis severity on the short- and long-term survival of COPD patients is limited. We hypothesized that COPD patients with severe acidosis would have a poorer short- and long-term prognosis compared with COPD patients with mild-to-moderate acidosis.

Patients and methods

This retrospective observational cohort study was conducted in a level III respiratory ICU of a tertiary teaching hospital for chest diseases between December 1, 2013, and December 30, 2014. Subject characteristics, comorbidities, ICU parameters, duration of mechanical ventilation, length of ICU stay, ICU mortality, use of domiciliary noninvasive mechanical ventilation (NIMV) and long-term oxygen therapy (LTOT), and short- and long-term mortality were recorded. Patients were grouped according to their arterial blood gas (ABG) values during ICU admission: severe acidotic (pH≤7.20) and mild-to-moderate acidotic (pH 7.21–7.35). These groups were compared with the recorded data. The mortality predictors were analyzed by logistic regression test in the ICU and the Cox regression test for long-term mortality predictors.

Results

During the study period, a total of 312 COPD patients admitted to the ICU with ARF, 69 (72.5% male) in the severe acidosis group and 243 (79% male) in the mild-to-moderate acidosis group, were enrolled. Group demographics, comorbidities, duration of mechanical ventilation, and length of ICU stay were similar in the two groups. The severe acidosis group had a significantly higher rate of NIMV failure (60.7% vs 40%) in the ICU. Mild-to-moderate acidotic COPD patients using LTOT had longer survival after ICU discharge than those without LTOT. On the other hand, severely acidotic COPD patients without LTOT showed shorter survival than those with LTOT. Kaplan–Meier cumulative survival analysis showed that the 28-day and 1-, 2-, and 3-year mortality rates were 12.2%, 36.2%, 52.6%, 63.3%, respectively (p=0.09). The Cox regression analyses showed that older age, PaO₂/FiO₂ <300 mmHg, and body mass index ≤20 kg/m² was associated with mortality of all patients after 3 years.

Conclusion

Severely acidotic COPD patients had a poorer short- and long-term prognosis compared with mild-to-moderate acidotic COPD patients if acute and chronic hypoxemia was predominant.

Restrictive lung disorder is common in patients with kidney failure and associates with protein-energy wasting, inflammation and cardiovascular disease

BACKGROUND

Cardiovascular disease (CVD), protein-energy wasting (PEW), and inflammation are common interrelated features of chronic kidney disease (CKD). Less is known about lung dysfunction in CKD and its possible role in this context. We evaluated lung function and its association with estimated glomerular filtration rate (GFR), CVD, PEW, and inflammation in individuals with normal to severely reduced GFR.

METHODS

In 404 individuals with GFR category G1 (n = 31; GFR >90mL/min/1.73 m2), G2 (n = 46), G3 (n = 33), G4 (n = 49) and G5 (n = 245; GFR<15mL/min/1.73 m2), pulmonary function was assessed by spirometry. Obstructive (OLD) and restrictive (RLD) lung dysfunction was defined based on forced vital capacity (FVC), forced expiratory volume in the first second (FEV1) and peak expiratory flow (PEF), expressed as percentages of predicted values (%FEV1, %FVC and %PEF, respectively). PEW was evaluated by subjective global assessment, handgrip strength (HGS) and lean body mass index (LBMI), and inflammation by interleukin-6 and high sensitivity C-reactive protein.

RESULTS

RLD (defined as FEV1/FVC ≥ 0.70 and %FVC<80) associated with GFR and was present in 36% of G5 and 14% of G1-4 individuals. OLD (FEV1/FVC<0.70) was less common with similar prevalence among G1-4 (9%) and G5 (11%) individuals. Notably, 64% of those with concomitant presence of PEW, inflammation and clinical signs of CVD had RLD while 79% of those lacking these complications had normal lung function. In multivariate logistic regression analysis, RLD associated with CVD, PEW and inflammation, after adjusting for Framingham's CVD risk score, serum albumin, and GFR category.

CONCLUSIONS

RLD is a common complication in patients with advanced CKD, especially in those with concomitant presence of CVD, inflammation and PEW. RLD appears to be an integral albeit scarcely explored consequence of pulmonary-renal interactions in CKD patients.

Is decreased lung function associated with chronic kidney disease? A retrospective cohort study in Korea

OBJECTIVE

There is some evidence that lung function and chronic kidney disease (CKD) may be related. We evaluated the impact of lung function on the development of CKD in a large-scale longitudinal study.

METHOD

Retrospective longitudinal analyses were conducted among subjects who participated in comprehensive health check-ups at least four times during 7 years (between 2006 and 2012). We investigated the development of CKD during the follow-up period according to lung function status.

RESULTS

Ten thousand one hundred and twenty-eight individuals (mean age =51.2 years) without CKD at baseline were enrolled. During the mean follow-up of 5 years (58.5±14.4 months), 167 of the 10 128 subjects (1.6%) developed CKD. Multivariable Cox proportional hazards analyses adjusting for age, sex, body mass index, systolic blood pressure, fasting glucose, estimated glomerular filtration rate, uric acid, triglycerides, serum albumin, and the presence of diabetes and hypertension revealed that a decrease of 10% in the forced expiratory volume in 1s (FEV₁)/forced vital capacity (FVC) ratio was associated with a 35% increase in the development of CKD during the follow-up. The incidence of CKD was higher in those with an FEV₁/FVC ratio <0.8 compared with those with FEV₁/FVC ratio ≥0.8 (HR=1.454; 95% CI 1.042 to 2.028, p=0.028).

CONCLUSIONS

Limited airflow as measured by the FEV₁/FVC ratio was associated with an increased risk of CKD.

Lung Function and Incident Kidney Disease: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Reduced lung function is associated with clinical outcomes such as cardiovascular disease. However, little is known about its association with incident end-stage renal disease (ESRD) and chronic kidney disease (CKD).

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

14,946 participants aged 45 to 64 years at baseline (1987-1989) in the Atherosclerosis Risk in Communities (ARIC) Study (45.0% men and 25.2% black), with follow-up through 2012.

PREDICTORS

Race- and sex-specific quartiles of percent-predicted forced vital capacity (FVC) and the proportion of forced expiratory volume in 1 second of expiration to FVC (FEV1/FVC) at baseline determined with spirometry.

OUTCOMES

Incident ESRD (defined here as renal replacement therapy or death due to CKD) as the primary outcome and incident CKD (defined here as ESRD, ≥25% decline in estimated glomerular filtration rate to a level <60mL/min/1.73m2, or CKD-related hospitalizations/deaths) as the secondary outcome.

RESULTS

During a median follow-up of 23.6 years, 526 (3.5%) participants developed ESRD. After adjusting for potential confounders, the cause-specific HR of incident ESRD for the lowest (vs highest) quartile was 1.72 (95% CI, 1.31-2.26) for percent-predicted FVC and 1.33 (95% CI, 1.03-1.73) for FEV1/FVC. Compared to a high-normal lung function pattern, a mixed pattern (ie, percent-predicted FVC<80% and FEV1/FVC<70%; 3.4% of participants) demonstrated the highest adjusted cause-specific HR of ESRD at 2.28 (95% CI, 1.50-3.45), followed by the restrictive pattern (ie, percent-predicted FVC<80% and FEV1/FVC≥70%; 4.8% of participants) at 2.03 (95% CI, 1.47-2.81), obstructive pattern (ie, percent-predicted FVC≥80% and FEV1/FVC<70%; 18.9% of participants) at 1.47 (95% CI, 1.09-1.99), and low-normal pattern (ie, percent-predicted FVC 80%-<100% and FEV1/FVC≥70%, or percent-predicted FVC≥80% and FEV1/FVC 70%-<75%; 44.3% of participants) at 1.21 (95% CI, 0.94-1.55). Similar associations were seen with incident CKD.

LIMITATIONS

Limited number of participants with moderate/severe lung dysfunction and spirometry only at baseline.

CONCLUSIONS

Reduced lung function, particularly lower percent-predicted FVC, is independently associated with CKD progression. Our findings suggest a potential pathophysiologic contribution of reduced lung function to the development of CKD and a need for monitoring kidney function in persons with reduced lung function.

A Pilot Study Linking Endothelial Injury in Lungs and Kidneys in Chronic Obstructive Pulmonary Disease

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) frequently have albuminuria (indicative of renal endothelial cell injury) associated with hypoxemia.

OBJECTIVES

To determine whether (1) cigarette smoke (CS)-induced pulmonary and renal endothelial cell injury explains the association between albuminuria and COPD, (2) CS-induced albuminuria is linked to increases in the oxidative stress-advanced glycation end products (AGEs) receptor for AGEs (RAGE) pathway, and (3) enalapril (which has antioxidant properties) limits the progression of pulmonary and renal injury by reducing activation of the AGEs-RAGE pathway in endothelial cells in both organs.

METHODS

In 26 patients with COPD, 24 ever-smokers without COPD, 32 nonsmokers who underwent a renal biopsy or nephrectomy, and in CS-exposed mice, we assessed pathologic and ultrastructural renal lesions, and measured urinary albumin/creatinine ratios, tissue oxidative stress levels, and AGEs and RAGE levels in pulmonary and renal endothelial cells. The efficacy of enalapril on pulmonary and renal lesions was assessed in CS-exposed mice.

MEASUREMENTS AND MAIN RESULTS

Patients with COPD and/or CS-exposed mice had chronic renal injury, increased urinary albumin/creatinine ratios, and increased tissue oxidative stress and AGEs-RAGE levels in pulmonary and renal endothelial cells. Treating mice with enalapril attenuated CS-induced increases in urinary albumin/creatinine ratios, tissue oxidative stress levels, endothelial cell AGEs and RAGE levels, pulmonary and renal cell apoptosis, and the progression of chronic renal and pulmonary lesions.

CONCLUSIONS

Patients with COPD and/or CS-exposed mice have pulmonary and renal endothelial cell injury linked to increased endothelial cell AGEs and RAGE levels. Albuminuria could identify patients with COPD in whom angiotensin-converting enzyme inhibitor therapy improves renal and lung function by reducing endothelial injury.

Rapid decline in lung function in healthy adults predicts incident excess urinary albumin excretion later in life

Introduction

Chronic lung disease, often characterised by rapid decline in lung function, is associated with vascular endothelial dysfunction (characterised by moderate to severe excess urinary albumin excretion (eUAE) but their longitudinal relationship is inadequately studied. In a bidirectional longitudinal examination of healthy adults, we analysed the following two hypotheses: (1) rapid decline (ie, highest tertile of lung function decline) predicts eUAE and (2) eUAE predicts rapid decline.

Methods

We performed a secondary data analysis from 3052 eligible participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study. For analysis 1, the predictor was rapid decline in lung function between the peak value (attained at or before CARDIA visit year 10 or Y10 at a mean age of 35 years) and Y20; and the outcome was incident eUAE at Y20 and/or Y25. For analysis 2, the predictor was eUAE at Y10 and the outcome was rapid decline between Y10 and Y20.

Results

After adjustment for covariates in analysis 1, rapid decline in FEV₁ or FVC between peak and Y20 predicted incident eUAE at Y20 and/or Y25 (OR 1.51 and 1.44, respectively; p≤0.05 for both analyses). In analysis 2, eUAE at Y10 did not predict subsequent rapid decline.

Conclusions

Healthy adults with rapid decline in lung function are at risk for developing vascular endothelial dysfunction, as assessed by incident eUAE, later in life.

Association between pulmonary function and renal function: findings from China and Australia

Background

The relationship between obstructive lung function and impaired renal function is unclear. This study investigated the dose-response relationship between obstructive lung function and impaired renal function.

Methods

Two independent cross-sectional studies with representative sampling were applied. 1454 adults from rural Victoria, Australia (1298 with normal renal function, 156 with impaired renal function) and 5824 adults from Nanjing, China (4313 with normal renal function, 1511 with impaired renal function). Pulmonary function measurements included forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Estimated glomerular filtration rate (eGFR), and impaired renal function marked by eGFR <60 mL/min/1.73m² were used as outcome.

Results

eGFR increased linearly with FEV1 in Chinese participants and with FVC in Australians. A non-linear relationship with peaked eGFR was found for FEV1 at 2.65 L among Australians and for FVC at 2.78 L among Chinese participants, respectively. A non-linear relationship with peaked eGFR was found for the predicted percentage value of forced expiratory volume in 1 s (PFEV1) at 81–82% and for the predicted percentage value of forced vital capacity (PFVC) at 83–84% among both Chinese and Australian participants, respectively.

The non-linear dose-response relationships between lung capacity measurements (both for FEV1 and FVC) and risk of impaired renal function were consistently identified in both Chinese and Australian participants. An increased risk of impaired renal function was found below 3.05 L both for FEV1 and FVC, respectively. The non-linear relationship between PFEV and PVC and the risk of impaired renal function were consistently identified in both Chinese and Australian participants. An increased risk of impaired renal function was found below 76–77% for PFEV1 and 79–80% for PFVC, respectively.

Conclusions

In both Australian and Chinese populations, the risk of impaired renal function increased both with FEV1 and FVC below 3.05 L, with PFEV1 below 76–77% or with PFVC below 79–80%, respectively. Obstructive lung function was associated with increased risk of reduced renal function. The screen for impaired renal function in patients with obstructive lung disease might be useful to ensure there was no impaired renal function before the commencement of potentially nephrotoxic medication where indicated (eg diuretics).

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0565-y) contains supplementary material, which is available to authorized users.

Impact of chronic kidney disease among Korean adults with chronic obstructive pulmonary disease

PURPOSE

Chronic kidney disease (CKD) is an emerging issue in patients with chronic obstructive pulmonary disease (COPD). In COPD, loss of muscle mass is relatively common finding, and diagnosis of CKD should be based on measured or estimated GFR (Cavailles et al. Eur Respir Rev 22:454-475, 2013; Gosker et al. Am J Clin Nutr 71:1033-1047, 2000; Delanaye and Mariat Nat Rev Nephrol 9:513-522, 2013). We aimed to determine the prevalence and impact of CKD, defined by using chronic kidney disease epidemiology collaboration (CKD-EPI) equation, in COPD patients.

METHODS

This study analyzed data of 3393 adults 40 years of age or older who completed pulmonary function tests in the fifth Korea National Health and Nutritional Examination Survey 2012. Participants with normal lung function (NLF) and COPD were included. CKD was defined as an eGFR <60 mL/min/1.73 m². Multivariate logistic regression analysis was performed to evaluate the relationship between CKD and COPD.

RESULTS

Among 3393 participants, 528 (15.6%) were classified as COPD. The prevalence values of participants with eGFR level ≥90, 60-90, and <60 mL/min/1.73 m² were 54.1, 43.6, and 2.2% in those with NLF and 39.8, 51.5, and 8.7% in those with COPD (p = 0.000). We analyzed the relationship between COPD and all factors that had a statistically significant association with COPD. The significant factors were older age, lower education, BMI, pulmonary tuberculosis, current bronchial asthma, smoking, and CKD.

CONCLUSIONS

In a Korean population ≥40 years old, the prevalence of participants with COPD is 15.6%. CKD is an independent risk factor for COPD. In addition to CKD, older age, lower education, BMI, pulmonary tuberculosis, current bronchial asthma, and smoking are significantly associated with COPD.

Lung function and impaired kidney function in relation to metabolic syndrome

PURPOSE

This study aimed to assess the relationships between abnormal lung function and indicators of chronic kidney disease in relation to metabolic syndrome (MetS) by using data from the 2011-2013 Korea National Health and Nutrition Examination Survey.

METHODS

Using the data of 8551 Korean adults (3798 men, 4753 women, ≥40 years), lung function categories [obstructive lung disease (OLD), restrictive lung disease (RLD), and non-obstructive/non-restrictive lung disease (reference group)] were defined for each gender. Albuminuria and low estimated glomerular filtration rate (eGFR) were defined as urine albumin-to-creatinine ratio ≥30 mg/g and eGFR < 60 mL/min/1.73 m². Gender-specific logistic regression analysis was performed after adjusting for age, educational level, smoking, alcohol use, physical activity, and medication use for chronic diseases.

RESULTS

Compared to the reference group, low eGFR was associated with higher odds for RLD in men and RLD or OLD in women when they did not have MetS. In those with MetS, low eGFR was associated with higher odds for OLD in men and RLD or OLD in women. Albuminuria was associated with higher odds for RLD in men who did not have MetS, while it was associated with higher odds for RLD or OLD in men and women who had MetS.

CONCLUSIONS

Abnormal lung function was associated with increased odds for chronic kidney disease indicators, when combined with MetS in both gender. Even in those without MetS, RLD in men was associated with increased odds for low eGFR or albuminuria, while RLD or OLD in women was associated with increased odds for low eGFR.

Prevalence of chronic kidney disease in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

Background

The incidence and prevalence of chronic kidney disease (CKD) continue to rise worldwide. Increasing age, diabetes, hypertension, and cigarette smoking are well-recognized risk factors for CKD. Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation leading to airway obstruction and parenchymal lung destruction. Due to some of the common pathogenic mechanisms, COPD has been associated with increased prevalence of CKD.

Methods

Systematic review of medical literature reporting the incidence and prevalence of CKD in patients with COPD using the Cochrane Collaboration Methodology, and conduct meta-analysis to study the cumulative effect of the eligible studies. We searched Medline via Ovid, PubMed, EMBASE and ISI Web of Science databases from 1950 through May, 2016. We included prospective and retrospective observational studies that reported the prevalence of CKD in patients with COPD.

Results

Our search resulted in 19 eligible studies of which 9 have been included in the meta-analysis. The definition of CKD was uniform across all the studies included in analysis. COPD was found to be associated with CKD in the included epidemiological studies conducted in many countries. Our meta-analysis showed that COPD was found to be associated with a significantly increased prevalence of CKD (Odds Ratio [OR] = 2.20; 95% Confidence Interval [CI] 1.83, 2.65). Study limitations: Studies included are observational studies. However, given the nature of our research question there is no possibility to perform a randomized control trial.

Conclusions

Patients with COPD have increased odds of developing CKD. Future research should investigate the pathophysiological mechanism behind this association, which may lead to better outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0315-0) contains supplementary material, which is available to authorized users.

Chronic Obstructive Pulmonary Disease is associated with risk of Chronic Kidney Disease: A Nationwide Case-Cohort Study

Patients with chronic obstructive pulmonary disease (COPD) and chronic kidney disease (CKD) share common risk factors. However, there is limited information about COPD and CKD. This is case-cohort study was carried out using the Taiwanese National Health Insurance Research Database to evaluate the correlation between COPD and CKD. We identified cases aged older than 40 years who had an inpatient hospitalization with a first-time COPD diagnosis between 1998 and 2008. Control were selected from hospitalized patients without COPD or CKD and were matched according to age, gender, and year of admission at a 2:1 ratio. Cox proportional hazards model was used to assess the association of CKD and COPD. The overall incidence of CKD was higher in the COPD group (470.9 per 10⁴ person-years) than in the non-COPD group (287.52 per 10⁴ person-years). The adjusted hazard ratio of case was 1.61 (P < 0.0001) times that of control. COPD was found to be associated with kidney disease from our follow-up. To detect CKD early, early diagnosis of CKD in patients with COPD and prompt initiation of monitoring and treatment are imperative.

Obstructive and Restrictive Lung Function Measures and CKD: National Health and Nutrition Examination Survey (NHANES) 2007-2012

BACKGROUND

Prevalence and factors associated with obstructive and restrictive lung function in people with chronic kidney disease (CKD) are unknown.

STUDY DESIGN

Cross-sectional and longitudinal analyses.

SETTING & PARTICIPANTS

Participants aged 40 to 79 years from NHANES (National Health and Nutrition Examination Survey) 2007 to 2012 who underwent spirometry testing.

PREDICTOR

CKD (estimated glomerular filtration rate [eGFR] >15-<60mL/min/1.73m(2) or urinary albumin-creatinine ratio ≥ 30mg/g).

OUTCOMES

Restrictive lung function (defined as FEV1/FVC≥0.70 and baseline FVC<80% predicted), obstructive lung function (defined as FEV1/FVC<0.70 based on postbronchodilator spirometric results), and mortality data (available for 2007-2008 and 2009-2010 survey periods).

RESULTS

7,610 participants (CKD=1,338; non-CKD=6,272) were included. Prevalences of obstructive lung function adjusted to the mean age of 55 years and 50% men in the CKD and non-CKD groups were 15.6% and 13.3%, respectively (P=0.2). Similarly, adjusted prevalences of restrictive lung function in the CKD and non-CKD groups were 9.8% and 6.7%, respectively (P=0.01). Presence of albumin-creatinine ratio ≥ 30mg/g was associated with obstructive (OR, 1.42; 95% CI, 1.07-1.88) and restrictive lung function (OR, 1.43; 95% CI, 1.01-2.03) in the entire study cohort. eGFR<60mL/min/1.73m(2) was associated with higher odds of obstructive lung function. In a multivariable Cox model, age (HR, 1.07; 95% CI, 1.04-1.11) and presence of obstructive lung function (HR, 2.68; 95% CI, 1.80-3.97), but not CKD measures, were associated with death.

LIMITATIONS

Small proportion of participants with advanced kidney disease.

CONCLUSIONS

In a representative sample of US adults, impaired lung function is common in those with and without CKD. Albuminuria was independently associated with both obstructive and restrictive lung function, and eGFR<60mL/min/1.73m(2) was associated with higher odds of obstructive lung function. Older age and obstructive lung function were associated with higher likelihood of death. Further studies examining the burden of lung disease in advanced CKD are needed.

Mortality Outcomes of Patients with Chronic Kidney Disease and Chronic Obstructive Pulmonary Disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with higher mortality in the general population. We studied the associations between COPD and death among chronic kidney disease (CKD) patients along with reporting cause-specific death data.

METHODS

We included 56,960 patients with stages 3 and 4 CKD who were followed in a large health care system. Associations between COPD and all-cause mortality and various causes of death (respiratory deaths, cardiovascular deaths, malignancy-related deaths and deaths due to other reasons) were studied using the Cox proportional hazards and competing risk models.

RESULTS

Out of 56,960 CKD patients, 4.7% (n = 2,667) had underlying COPD. Old age, presence of diabetes, hypertension, coronary artery disease, congestive heart failure, and smoking were associated with higher risk for COPD. During a median follow-up of 3.7 years, 15,969 patients died. After covariate adjustment, COPD was associated with a 41% increased risk (95% CI 1.31-1.52) for all-cause mortality, and fourfold increased risk (sub-hazard ratio 4.36, 95% CI 3.54-5.37) for respiratory-related deaths. In a sensitivity analysis that was performed by defining COPD as the use of relevant International Classification of Diseases-9 codes and medications used to treat COPD, similar results were noted.

CONCLUSIONS

COPD is associated with higher risk for death among those with CKD, and an underlying lung disease accounts for significant proportion of deaths. These data highlight the need for further prospective studies to understand the underlying mechanisms and potential interventions to improve outcomes in this population.

Prevalence of chronic kidney diseases in patients with chronic obstructive pulmonary disease: assessment based on glomerular filtration rate estimated from creatinine and cystatin C levels

Background

Cardiovascular diseases, osteoporosis, and depression are identified comorbidities of chronic obstructive pulmonary disease (COPD), but there have been few reports of chronic kidney disease (CKD) as a comorbidity of COPD. The objective of this study was to investigate the prevalence of CKD in COPD patients using estimated glomerular filtration rate (eGFR) based on creatinine (Cr) and cystatin C (Cys) levels.

Methods

The prevalence of CKD and the values of various CKD-related parameters were compared between 108 stable COPD outpatients (COPD group) and a non-COPD control group consisting of 73 patients aged 60 years or more without a history of COPD or kidney disease. CKD was defined as an eGFR less than 60 mL/min/1.73 m².

Results

The Cr level was significantly higher in the COPD group, but eGFR based on serum Cr (eGFR_Cr) was not significantly different between the two groups (73.3±25.3 vs 79.7±15.5 mL/min/1.73 m²). The Cys level was significantly higher and eGFR based on serum Cys (eGFR_Cys) was significantly lower in the COPD group (60.0±19.4 vs 74.0±13.5 mL/min/1.73 m², P<0.0001). The prevalence of CKD evaluated based on eGFR_Cr was 31% in the COPD group and 8% in the non-COPD group with an odds ratio of 4.91 (95% confidence interval, 1.94–12.46, P=0.0008), whereas the evaluated prevalence based on eGFR_Cys was 53% in the COPD group and 15% in the non-COPD group with an odds ratio of 6.30 (95% confidence interval, 2.99–13.26, P<0.0001), demonstrating a higher prevalence of CKD when based on eGFR_Cys rather than on eGFR_Cr.

Conclusion

CKD is a comorbidity that occurs frequently in COPD patients, and we believe that renal function in Japanese COPD patients should preferably be evaluated based not only on Cr but on Cr in combination with Cys.

Economic Burden of COPD in the Presence of Comorbidities

BACKGROUND

The morbidity and mortality associated with COPD exacts a considerable economic burden. Comorbidities in COPD are associated with poor health outcomes and increased costs. Our objective was to assess the impact of comorbidities on COPD-associated costs in a large administrative claims dataset.

METHODS

This was a retrospective observational study of data from the Truven Health MarketScan Commercial Claims and Encounters and the MarketScan Medicare Supplemental Databases from January 1, 2009, to September 30, 2012. Resource consumption was measured from the index date (date of first occurrence of non-rule-out COPD diagnosis) to 360 days after the index date. Resource use (all-cause and disease-specific [ie, COPD- or asthma-related] ED visits, hospitalizations, office visits, other outpatient visits, and total length of hospital stay) and health-care costs (all-cause and disease-specific costs for ED visits, hospitalizations, office visits, and other outpatient visits and medical, prescription, and total health-care costs) were assessed. Generalized linear models were used to evaluate the impact of comorbidities on total health-care costs, adjusting for age, sex, geographic location, baseline health-care use, employment status, and index COPD medication.

RESULTS

Among 183,681 patients with COPD, the most common comorbidities were cardiovascular disease (34.8%), diabetes (22.8%), asthma (14.7%), and anemia (14.2%). Most patients (52.8%) had one or two comorbidities of interest. The average all-cause total health-care costs from the index date to 360 days after the index date were highest for patients with chronic kidney disease ($41,288) and anemia ($38,870). The impact on total health-care costs was greatest for anemia ($10,762 more, on average, than a patient with COPD without anemia).

CONCLUSIONS

Our analysis demonstrated that high resource use and costs were associated with COPD and multiple comorbidities.

Low arterial blood oxygenation is associated with calcification of the coronary arteries in patients with chronic obstructive pulmonary disease

BACKGROUND

Cigarette smoking is a well-known major cause of both chronic obstructive pulmonary disease (COPD) and atherosclerosis. However, few studies have investigated the correlation between COPD and coronary atherosclerosis.

METHODS

We recruited 54 patients with stable COPD (51 men, 3 women) but without angina symptoms. Arterial blood gas analyses were performed, pulmonary function was assessed, and calcification of the coronary arteries was evaluated by computed tomography (CT).

RESULTS

Calcification of the coronary arteries was noted in 25 patients. There were no significant differences in age, body mass index, respiratory function, and levels of low-density lipoprotein cholesterol, hemoglobin A1c, glucose, or C-reactive protein between patients with or without calcification of the coronary arteries. Arterial blood oxygenation was significantly lower in patients with calcification of the coronary arteries. On both univariate and multivariate analyses, low arterial blood oxygenation was an independent risk factor for calcification of the coronary arteries.

CONCLUSIONS

In patients with COPD, low arterial blood oxygenation was strongly associated with calcification of the coronary arteries and may be a significant predictor of cardiovascular disease.

Risk of pneumonia among patients with chronic kidney disease in outpatient and inpatient settings: a nationwide population-based study

Patients with chronic kidney disease (CKD) are more at risk for pneumonia than the general population. Patients with pneumonia are usually treated as outpatients. However, previous studies were conducted on the basis of inpatient pneumonia. This method may underestimate the risk of pneumonia in patients with CKD. Therefore, we investigated the risk of pneumonia among CKD patients in both outpatient and inpatient settings. A total of 15,562 patients with CKD and 62,109 individuals without CKD (matched for age and gender) were taken as subjects in the Longitudinal Health Insurance Database of Taiwan National Insurance from 1996 to 2010. The incidence density rates of inpatient and outpatient pneumonia were calculated. The risk factors associated with pneumonia were analyzed using Cox proportional hazard models with adjustments for confounders. The incidence density rate of pneumonia was 65.6 per 1000 person-years in patients with CKD and 28.4 per 1000 person-years in individuals without CKD. The incidence density rate of inpatient pneumonia was 43.3 per 1000 person-years in patients with CKD and 16.6 per 1000 person-years in individuals without CKD. CKD was associated with increased risk of pneumonia (adjusted hazard ratio [aHR], 1.97; 95% confidence interval [CI], 1.89-2.05; P < 0.001), outpatient pneumonia (aHR, 1.40; 95% CI, 1.31-1.49), and inpatient pneumonia (aHR, 2.17; 95% CI, 2.07-2.29, P < 0.001). Patients' comorbidities, including diabetes, cardiovascular disease (CVD), asthma, and chronic obstructive pulmonary disease (COPD), were independently associated with increased risk of pneumonia.CKD is associated with the increased risk of both outpatient and inpatient pneumonia. This association is independent of comorbid diabetes, CVD, asthma, and COPD.

Renal and hepatobiliary dysfunction in chronic obstructive pulmonary disease

PURPOSE OF REVIEW

This review examines the associations between chronic obstructive pulmonary disease (COPD) and renal and hepatobiliary diseases, with emphasis on the epidemiology and clinical outcomes, along with current information on pathophysiologic mechanisms and risk factors.

RECENT FINDINGS

Glomerular filtration, sodium retention, and waste excretion are abnormal in COPD and sensitive to hypoxemia and hypercarbia, but variably responsive to oxygen administration and angiotensin-converting enzyme inhibition. Newer concepts about the role of hypoxia on the progression of chronic renal failure, and improved understanding about the relationships between COPD, decreased arterial compliance, and renal glomerular injury, are bringing new insights about potential causal mechanisms between COPD and kidney diseases. Other than the well known relationship between cor pulmonale and passive liver congestion, little was known about the relationships between COPD and liver diseases until recent population-based surveys demonstrated that COPD patients have substantially elevated risk for specific hepatobiliary system diseases.

SUMMARY

Renal complications of COPD are common especially among patients with hypoxemia and hypercarbia. Renal-endocrine mechanisms, tissue hypoxia, and vascular rigidity have roles in the pathophysiology, but understanding of causal relationships is not precise. COPD patients have increased risk for hepatobiliary diseases and asymptomatic elevations of hepatic transaminases, which fortunately have relatively low prevalence.

Prevalence of renal and hepatobiliary disease, laboratory abnormalities, and potentially toxic medication exposures among persons with COPD

Background

The purpose of this study was to describe the prevalence of renal and hepatic disease, related laboratory abnormalities, and potentially hepatotoxic and nephrotoxic medication use in a population-based cohort of persons with chronic obstructive pulmonary disease (COPD).

Methods

This was a retrospective case-control cohort analysis of COPD patients enrolled in one regional health system for at least 12 months during a 36-month study period (n = 2284). Each COPD patient was matched by age and gender to up to three persons not diagnosed with COPD (n = 5959).

Results

The mean age for cases and controls was 70.3 years, and 52.5% were women. The COPD cohort had significantly higher prevalences (cases/100) of acute, chronic, and unspecified renal failure as compared with controls (1.40 versus 0.59, 2.89 versus 0.79, and 1.09 versus 0.44, respectively). Among the cases, 31.3% had at least one renal or urinary tract diagnosis during the study period, as compared with 21.1% of controls. COPD cases also had more gallbladder disease (2.76 versus 1.63) and pancreatic disease (1.40 versus 0.60), but not hepatic disease. COPD patients were more likely to have at least one serum creatinine level (5.1 versus 2.1) or liver aspartate aminotransferase level (4.5 versus 2.7) that was more than twice the upper limit of normal. COPD patients had prescription fills for an average of 17.6 potentially nephrotoxic and 27.4 hepatotoxic drugs during the study period, as compared with 13.6 and 19.9 for the controls (P value for all comparisons < 0.01).

Conclusion

COPD patients have a substantially increased prevalence of renal, gallbladder, and pancreatic diseases, as well as abnormal renal and hepatic laboratory values, but not diagnosed liver disease. COPD patients are also more likely to be prescribed medications with potentially toxic renal or hepatic side effects.

The relationship between pulmonary emphysema and kidney function in smokers

BACKGROUND

It has been reported that the prevalence of kidney dysfunction may be increased in patients exposed to tobacco with airflow obstruction. We hypothesized that kidney dysfunction would associate with emphysema rather than with airflow obstruction measured by the FEV₁.

METHODS

Five hundred eight current and former smokers completed a chest CT scan, pulmonary function tests, medical questionnaires, and measurement of serum creatinine. Glomerular filtration rates (eGFRs) were estimated using the method of the Chronic Kidney Disease Epidemiology Collaboration. Quantitative determinants of emphysema and airway dimension were measured from multidetector chest CT scans.

RESULTS

The mean age was 66 ± 7 years, and mean eGFR was 101 ± 22 mL/min/1.73 m². Univariate and multivariate analysis showed a significant association between radiographically measured emphysema and eGFR: Participants with 10% more emphysema had an eGFR that was lower by 4.4 mL/min/1.73 m² (P = .01), independent of airflow obstruction (FEV₁), age, sex, race, height, BMI, diabetes mellitus, hypertension, coronary artery disease, patient-reported dyspnea, pack-years of smoking, and current smoking. There was no association between eGFR and either FEV₁ or quantitative CT scan measures of airway dimension.

CONCLUSIONS

More severe emphysema, rather than airflow obstruction, is associated with kidney dysfunction in tobacco smokers, independent of common risk factors for kidney disease. This finding adds to recent observations of associations between emphysema and comorbidities of COPD, including osteoporosis and lung cancer, which are independent of the traditional measure of reduced FEV₁. The mechanisms and clinical implications of kidney dysfunction in patients with emphysema need further investigation.

Chronic obstructive pulmonary disease: an independent risk factor for peptic ulcer bleeding: a nationwide population-based study

BACKGROUND

Peptic ulcer bleeding remains a major healthcare problem despite decreasing prevalence of peptic ulcer disease. The role of chronic obstructive pulmonary disease (COPD) in the risk of peptic ulcer bleeding has not yet been established.

AIM

To determine if COPD patients have a higher risk of peptic ulcer bleeding than the general population and to identify the risk factors of peptic ulcer bleeding in COPD patients.

METHODS

From Taiwan's National Health Insurance research database, 62,876 patients, including 32,682 COPD and 30,194 age-gender-matched non-COPD controls, were recruited. Cox proportional hazard regression was performed to evaluate independent risk factors for ulcer bleeding in all patients and to identify risk factors in COPD patients.

RESULTS

During the 8-year follow-up, COPD patients had a significant higher rate of peptic ulcer bleeding than the control group (P < 0.001, by log-rank test). By Cox proportional hazard regression analysis, COPD [hazard ratio (HR) 1.93, 95% CI 1.73-2.17] was an independent risk factor after adjusting for age, gender, underlying comorbidities and ulcerogenic medication. Age > 65 years, male, comorbidities of hypertension, diabetes, heart failure, history of peptic ulcer disease, and chronic renal disease and use of nonsteroidal anti-inflammatory drugs were risk factors of ulcer bleeding in COPD patients.

CONCLUSION

Patients with chronic obstructive pulmonary disease have a higher risk of peptic ulcer bleeding after adjustments for possible confounding factors like underlying comorbidities and ulcerogenic medication.

Acid-base disorders in patients with chronic obstructive pulmonary disease: a pathophysiological review

The authors describe the pathophysiological mechanisms leading to development of acidosis in patients with chronic obstructive pulmonary disease and its deleterious effects on outcome and mortality rate. Renal compensatory adjustments consequent to acidosis are also described in detail with emphasis on differences between acute and chronic respiratory acidosis. Mixed acid-base disturbances due to comorbidity and side effects of some drugs in these patients are also examined, and practical considerations for a correct diagnosis are provided.

C-reactive protein levels, airflow obstruction, and chronic kidney disease

OBJECTIVES

There is some evidence that chronic obstructive pulmonary disease and chronic kidney disease (CKD) may be related, perhaps through systemic inflammation, which is common to both. However, this relationship has not yet been clearly demonstrated. The aim of this study was to investigate the association between airflow obstruction, CKD, and C-reactive protein (CRP) levels in Japanese men.

METHODS

The study included 11,587 men, aged 40-88 years, who underwent a health check-up. Airflow obstruction was defined as a forced expiratory volume in 1 s/forced vital capacity of <70%, and its severity was based on the Global Initiative for Chronic Obstructive Lung Disease guidelines (GOLD). CKD was defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m(2).

RESULTS

Airflow obstruction was present in 7.9% of the participants, and 10.6% of the participants had CKD. The average CRP levels were 0.11 ± 0.36, 0.13 ± 0.41, and 0.18 ± 0.41 mg/L for subjects with normal lung function, GOLD stage I, and GOLD stage II-IV, respectively. With regard to CKD, the average CRP levels were 0.11 ± 0.32 and 0.18 ± 0.6 mg/L for subjects without and with CKD, respectively. Analysis of covariance showed no significant differences between the CRP level and lung function status or CKD after age was adjusted for. Logistic regression analysis showed no association among subjects with the three different lung function statuses after age, body mass index, hypertension, diabetes, hyper-low-density-lipoprotein-cholesterolemia, smoking, physical activity, and alcohol intake were controlled for.

CONCLUSIONS

Based on the results of this study, we conclude that there is no interrelationship between CRP level, airflow obstruction, and CKD.

Systemic manifestations of COPD

COPD is characterized by a poorly reversible airflow limitation resulting from chronic inflammation, mainly due to tobacco exposure. Over the past few years, the understanding of COPD has evolved from it being a disease affecting the lungs to it being a complex, heterogeneous, and generalized disorder in an aging population. Extrapulmonary comorbidities significantly complicate the management and influence the prognosis of patients with COPD. Although certain comorbidities like cardiovascular diseases share some risk factors with COPD, such as cigarette smoking, other frequently observed comorbidities, including musculoskeletal wasting, metabolic syndrome, and depression, cannot be easily attributed to smoking. There is increasing evidence that chronic inflammation is a key factor in COPD and that inflammation might be the common pathway linking these comorbidities and explaining why they typically develop together. Physicians treating patients with COPD need to become aware of these extrapulmonary aspects. Any patient with COPD should be carefully evaluated for comorbidities and the systemic consequences of COPD since they not only influence the prognosis but also have an impact on disease management. The treatment of COPD is no longer focused exclusively on inhaled therapy but is taking on a multidimensional approach, especially because the treatment of the comorbidities might positively affect the course of COPD itself.

The suffocating kidney: tubulointerstitial hypoxia in end-stage renal disease

Chronic kidney disease (CKD) is characterized by irreversible pathological processes that result in the development of end-stage renal disease (ESRD). Accumulating evidence has emphasized the important role of chronic hypoxia in the tubulointerstitium in the final common pathway that leads to development of ESRD. The causes of chronic hypoxia in the tubulointerstitium are multifactorial and include mechanisms such as hemodynamic changes and disturbed oxygen metabolism of resident kidney cells. Epidemiological studies have revealed an association between CKD and systemically hypoxic conditions, such as chronic obstructive pulmonary disease and sleep apnea syndrome. In addition to tubulointerstitial hypoxia, glomerular hypoxia can occur and is a crucial factor in the development of glomerular disorders. Chemical compounds, polarographic sensors, and radiographical methods can be used to detect hypoxia. Therapeutic approaches that target chronic hypoxia in the kidney should be effective against a broad range of kidney diseases. Amelioration of hypoxia is one mechanism of inhibiting the renin-angiotensin system, the current gold standard of CKD therapy. Future therapeutic approaches include protection of the vascular endothelium and appropriate activation of hypoxia-inducible factor, a key transcription factor involved in adaptive responses against hypoxia.