Seungsoo Sheen

Testing a tool for assessing the risk of bias for nonrandomized studies showed moderate reliability and promising validity

OBJECTIVESnTo develop and validate a new risk-of-bias tool for nonrandomized studies (NRSs).nnnSTUDY DESIGN AND SETTINGnWe developed the Risk of Bias Assessment Tool for Nonrandomized Studies (RoBANS). A validation process with 39 NRSs examined the reliability (interrater agreement), validity (the degree of correlation between the overall assessments of RoBANS and Methodological Index for Nonrandomized Studies [MINORS], obtained by plotting the overall risk of bias relative to effect size and funding source), face validity with eight experts, and completion time for the RoBANS approach.nnnRESULTSnRoBANS contains six domains: the selection of participants, confounding variables, the measurement of exposure, the blinding of the outcome assessments, incomplete outcome data, and selective outcome reporting. The interrater agreement of the RoBANS tool except the measurement of exposure and selective outcome reporting domains ranged from fair to substantial. There was a moderate correlation between the overall risks of bias determined using RoBANS and MINORS. The observed differences in effect sizes and funding sources among the assessed studies were not correlated with the overall risk of bias in these studies. The mean time required to complete RoBANS was approximately 10 min. The external experts who were interviewed evaluated RoBANS as a fair assessment tool.nnnCONCLUSIONSnRoBANS shows moderate reliability, promising feasibility, and validity. The further refinement of this tool and larger validation studies are required.

Usefulness of the index of microcirculatory resistance for invasively assessing myocardial viability immediately after primary angioplasty for anterior myocardial infarction.

AIMSnThe aim of this study is to evaluate the usefulness of the index of microcirculatory resistance (IMR) for predicting myocardial viability and left ventricular (LV) function recovery in acute myocardial infarction (AMI).nnnMETHODS AND RESULTSnAfter successful primary percutaneous coronary intervention in 40 patients with anterior AMI, IMR was measured using a pressure-temperature sensor-tipped coronary guidewire. Myocardial viability was quantified by 18F-fluorodeoxyglucose (FDG) positron emission tomography in 38 patients. Echocardiographic regional wall motion was analysed to calculate the anterior wall motion score (A-WMS) and percent change in A-WMS after revascularization and at 6-month follow-up. IMR correlated significantly with regional myocardial FDG uptake (r = -0.738, P < 0.001) and it demonstrated significant correlation with percent change in A-WMS (r = -0.464, P = 0.003). The area under the receiver operating curve of IMR for predicting LV function recovery was 0.89 [95% CI 0.888-0.894].nnnCONCLUSIONnIndex of microcirculatory resistance, a new index representing microvascular integrity, is a reliable early on-site determinant of myocardial viability and LV recovery after primary stenting for AMI.

A newly developed tool for classifying study designs in systematic reviews of interventions and exposures showed substantial reliability and validity

OBJECTIVEnTo develop a study Design Algorithm for Medical Literature on Intervention (DAMI) and test its interrater reliability, construct validity, and ease of use.nnnSTUDY DESIGN AND SETTINGnWe developed and then revised the DAMI to include detailed instructions. To test the DAMIs reliability, we used a purposive sample of 134 primary, mainly nonrandomized studies. We then compared the study designs as classified by the original authors and through the DAMI. Unweighted kappa statistics were computed to test interrater reliability and construct validity based on the level of agreement between the original and DAMI classifications. Assessment time was also recorded to evaluate ease of use.nnnRESULTSnThe DAMI includes 13 study designs, including experimental and observational studies of interventions and exposure. Both the interrater reliability (unweighted kappaxa0=xa00.67; 95% CI [0.64-0.75]) and construct validity (unweighted kappaxa0=xa00.63, 95% CI [0.52-0.67]) were substantial. Mean classification time using the DAMI was 4.08xa0±xa02.44xa0minutes (range, 0.51-10.92).nnnCONCLUSIONSnThe DAMI showed substantial interrater reliability and construct validity. Furthermore, given its ease of use, it could be used to accurately classify medical literature for systematic reviews of interventions although minimizing disagreement between authors of such reviews.

An updated review of case-control studies of lung cancer and indoor radon-Is indoor radon the risk factor for lung cancer?

Lung cancer is a leading cause of cancer-related death in the world. Smoking is definitely the most important risk factor for lung cancer. Radon (222Rn) is a natural gas produced from radium (226Ra) in the decay series of uranium (238U). Radon exposure is the second most common cause of lung cancer and the first risk factor for lung cancer in never-smokers.Case–control studies have provided epidemiological evidence of the causative relationship between indoor radon exposure and lung cancer. Twenty-four case–control study papers were found by our search strategy from the PubMed database. Among them, seven studies showed that indoor radon has a statistically significant association with lung cancer. The studies performed in radon-prone areas showed a more positive association between radon and lung cancer. Reviewed papers had inconsistent results on the dose–response relationship between indoor radon and lung cancer risk.Further refined case–control studies will be required to evaluate the relationship between radon and lung cancer. Sufficient study sample size, proper interview methods, valid and precise indoor radon measurement, wide range of indoor radon, and appropriate control of confounders such as smoking status should be considered in further case–control studies.

Onset time of hyperkalaemia after angiotensin receptor blocker initiation: when should we start serum potassium monitoring?

Angiotensin receptor blockers (ARBs) frequently induce hyperkalaemia in high‐risk patients. Early detection of hyperkalaemia can reduce the subsequent harmful effects. This study was performed to examine the onset time of hyperkalaemia after ARB therapy.

Emphysematous phenotype is an independent predictor for frequent exacerbation of COPD.

SETTINGnFrequent exacerbation is an important phenotype in chronic obstructive pulmonary disease (COPD), while emphysema is associated with many comorbidities and lung function decline.nnnOBJECTIVEnTo investigate unique features of frequent exacerbators and test the hypothesis that emphysematous phenotype is associated with frequent exacerbations of COPD.nnnMETHODSnA total of 380 COPD patients were recruited from 16 hospitals in Korea from June 2005 to April 2012 for analysis. We searched for independent predictors of frequent exacerbators in comparison with non-exacerbators.nnnRESULTSnAs the severity of emphysema increased, forced expiratory volume in 1 s (FEV₁), and FEV₁/FVC (forced volume capacity) worsened; hyperinflationary features characterised by higher total lung capacity (TLC) were observed (P < 0.05). Frequent exacerbators had lower body mass index (BMI), higher St Georges Respiratory Questionnaire (SGRQ) scores, higher residual volume (RV)/TLC, more severe airflow limitation (lower FEV₁ and FEV₁/FVC), lower carbon monoxide diffusion capacity, lower serum protein levels and a higher emphysema index than non-exacerbators (P < 0.05). In multivariate analysis, frequent exacerbators were independently associated with a higher emphysema index, lower serum protein levels and higher RV/TLC (P < 0.05).nnnCONCLUSIONnOur data show that the severity of emphysema, severe static hyperinflation and serum lower protein levels are independent predictors of frequent exacerbations in COPD patients.

Assessment of the Quality of Clinical Practice Guidelines in Korea Using the AGREE Instrument

The objective of this study was to conduct the systematic evaluation of methodological quality of clinical practice guidelines (CPGs) in Korea. The authors conducted a very comprehensive literature search to identify potential CPGs for evaluation. CPGs were selected which were consistent with a predetermined criteria. Four reviewers evaluated the quality of the CPGs using the Appraisal of Guidelines, Research and Evaluation (AGREE) Instrument. AGREE item scores and standardized domain scores were calculated. The inter-rater reliability of each domain was evaluated using the intra-class correlation coefficient (ICC). Consequently, 66 CPGs were selected and their quality evaluated. ICCs for CPG appraisal using the AGREE Instrument ranged from 0.626 to 0.877. Except for the Scope and Purpose and Clarity and Presentation domains, 80% of CPGs scored less than 40 in all other domains. This review shows that many Korean research groups and academic societies have made considerable efforts to develop CPGs, and the number of CPGs has increased over time. However, the quality of CPGs in Korea were not good according to the AGREE Instrument evaluation. Therefore, we should make more of an effort to ensure the high quality of CPGs.

The Prognostic Value of Residual Volume/Total Lung Capacity in Patients with Chronic Obstructive Pulmonary Disease.

The prognostic role of resting pulmonary hyperinflation as measured by residual volume (RV)/total lung capacity (TLC) in chronic obstructive pulmonary disease (COPD) remains poorly understood. Therefore, this study aimed to identify the factors related to resting pulmonary hyperinflation in COPD and to determine whether resting pulmonary hyperinflation is a prognostic factor in COPD. In total, 353 patients with COPD in the Korean Obstructive Lung Disease cohort recruited from 16 hospitals were enrolled. Resting pulmonary hyperinflation was defined as RV/TLC ≥ 40%. Multivariate logistic regression analysis demonstrated that older age (P = 0.001), lower forced expiratory volume in 1 second (FEV1) (P < 0.001), higher St. George Respiratory Questionnaire (SGRQ) score (P = 0.019), and higher emphysema index (P = 0.010) were associated independently with resting hyperinflation. Multivariate Cox regression model that included age, gender, dyspnea scale, SGRQ, RV/TLC, and 6-min walking distance revealed that an older age (HR = 1.07, P = 0.027), a higher RV/TLC (HR = 1.04, P = 0.025), and a shorter 6-min walking distance (HR = 0.99, P < 0.001) were independent predictors of all-cause mortality. Our data showed that older age, higher emphysema index, higher SGRQ score, and lower FEV1 were associated independently with resting pulmonary hyperinflation in COPD. RV/TLC is an independent risk factor for all-cause mortality in COPD. Graphical Abstract

Different therapeutic responses in chronic obstructive pulmonary disease subgroups

SETTINGnEleven referring hospitals in South Korea.nnnOBJECTIVEnTo compare therapeutic responses in chronic obstructive pulmonary disease (COPD) subgroups, classified by diffusing capacity of the lung for carbon monoxide (DL(CO)) and lung volume.nnnDESIGNnA total of 130 stable male COPD patients were classified into four subgroups according to baseline DL(CO) and residual volume/total lung capacity (RV/TLC) ratio. We compared therapeutic responses to short acting β(2)-agonist (SABA) and 3-month combined inhalation of long-acting β(2)-agonist (LABA) and corticosteroid among patients with these subgroups.nnnRESULTSnAmong the 130 COPD patients, 41 (31.5%) had normal DL(CO) and RV/TLC, 28 (21.5%) low DL(CO) and normal RV/TLC, 31 (23.8%) normal DL(CO) and high RV/TLC, and 30 (23.1%) low DL(CO) and high RV/TLC. The normal DL(CO)/high RV/TLC subgroup showed a significantly larger flow response (changes in forced expiratory volume in 1 s) to salbutamol than the normal DL(CO)/RV/TLC subgroups, and a larger volume response (changes in forced vital capacity) than the two normal RV/TLC subgroups. The normal DL(CO)/high RV/TLC subgroup also showed significantly larger flow and volume response to 3-month combined inhalation of LABA and corticosteroid than the two normal RV/TLC subgroups.nnnCONCLUSIONnCOPD subgroups classified by DL(CO) and RV/TLC may have different pulmonary function responses to pharmacological treatment.

Pulmonary artery pressure in chronic obstructive pulmonary disease without resting hypoxaemia.

BACKGROUNDnChronic obstructive pulmonary disease (COPD) can lead to pulmonary hypertension and cor pulmonale, which are predictors of mortality.nnnOBJECTIVEnTo identify predictors of increased pulmonary artery pressure (PAP) in COPD patients without resting hypoxaemia, and to characterise COPD patients with increased PAP.nnnDESIGNnA study of 117 COPD patients from the Korean Obstructive Lung Disease (KOLD) cohort who had measurable tricuspid regurgitant flow under transthoracic Doppler echocardiography and no resting hypoxaemia.nnnRESULTSnThe mean patient age was 67 years. Mean forced expiratory volume in 1 second (FEV(1)) was 47% predicted, mean haemoglobin (Hb) concentration was 145 g/l and mean systolic PAP (sPAP) was 33 mmHg. Multiple linear regression analysis showed that Hb was the only factor independently associated with sPAP (beta = -1.752, P = 0.005). Cluster analysis using FEV(1)% predicted, sPAP and Hb concentration as variables indicated three patient clusters: Cluster 1 (n = 36; mean FEV(1) 44% predicted, mean sPAP 39 mmHg, mean Hb 132 g/l), Cluster 2 (n = 45; FEV(1) 35% predicted, sPAP 31 mmHg, Hb 154 g/l), and Cluster 3 (n = 36; FEV(1) 65% predicted, sPAP 29 mmHg, Hb 148 g/l).nnnCONCLUSIONnElevated PAP was linked to low haemoglobin levels in COPD without resting hypoxaemia.