Muhammad Shahzeb Khan

The top 100 cited articles published in emergency medicine journals

INTRODUCTION Our objective was to identify trends and examine the characteristics of the top 100 cited articles in emergency medicine (EM) journals. METHODS Scopus Library database was queried to determine the citations of the top 100 EM articles. A second database (Google Scholar) was used to gather the following information: number of authors, publication year, journal name, impact factor, country of origin, and article type (original article, review article, conference paper, or editorial). The top 100 cited articles were selected and analyzed by 2 independent investigators. RESULTS We identified 100 top-cited articles published in 6 EM journals, led by Annals of Emergency Medicine (65) and American Journal of Emergency Medicine (15). All top-cited articles were published between 1980 and 2009. The common areas of study were categorized as cardiovascular medicine, emergency department administration, toxicology, pain medicine, pediatrics, traumatology, and resuscitation. A statistically significant association was found between the journal impact factor and the number of top 100 cited articles (P < .005). CONCLUSION The top-cited articles published in EM journals help us recognize the quality of the works, discoveries, and trends steering EM. Our analysis provides an insight to the prevalent areas of study being cited within our field of practice.

Top 100 cited articles in cardiovascular magnetic resonance: a bibliometric analysis

BackgroundWith limited health care resources, bibliometric studies can help guide researchers and research funding agencies towards areas where reallocation or increase in research activity is warranted. Bibliometric analyses have been published in many specialties and sub-specialties but our literature search did not reveal a bibliometric analysis on Cardiovascular Magnetic Resonance (CMR). The main objective of the study was to identify the trends of the top 100 cited articles on CMR research.MethodsWeb of Science (WOS) search was used to create a database of all English language scientific journals. This search was then cross-referenced with a similar search term query of Scopus® to identify articles that may have been missed on the initial search. Articles were ranked by citation count and screened by two independent reviewers.ResultsCitations for the top 100 articles ranged from 178 to 1925 with a median of 319.5. Only 17 articles were cited more than 500 times, and the vast majority (n = 72) were cited between 200–499 times. More than half of the articles (n = 52) were from the United States of America, and more than one quarter (n = 21) from the United Kingdom. More than four fifth (n = 86) of the articles were published between the time period 2000–2014 with only 1 article published before 1990. Circulation and Journal of the American College of Cardiology made up more than half (n = 62) of the list. We found 10 authors who had greater than 5 publications in the list.ConclusionOur study provides an insight on the characteristics and quality of the most highly cited CMR literature, and a list of the most influential references related to CMR.

Bibliometric analysis of the top 50 cited respiratory articles

Background: Citation classics have been published in almost all medical fields. The main objective of this study was to provide the readers with a complete updated guide using two different citation tracking sources in assessing respiratory literature published in respiratory specific or general medical journals. Methods: Scopus Library database (www.scopus.com) was used to determine the 50 most cited articles regarding respiratory medicine using the subject category “respiratory system.” The results from the database were sorted using the option “Times cited.” Results: The top 50 articles were published during the time period 1987–2008, with most articles (n = 22) published from 1996 to 2000.The topic that had the highest number of articles (n = 15) was chronic obstructive pulmonary disorders (COPD) followed by asthma (n = 10). Conclusion: A periodic evaluation of the top cited articles can help researchers identify the quality of work in respiratory system and pinpoint subtopics which have not been given due consideration.

Safety and Use of Anticoagulation After Aortic Valve Replacement With Bioprostheses: A Meta-Analysis

Background—The American College of Cardiology guidelines recommend 3 months of anticoagulation after replacement of the aortic valve with a bioprosthesis. However, there remains great variability in the current clinical practice and conflicting results from clinical studies. To assist clinical decision making, we pooled the existing evidence to assess whether anticoagulation in the setting of a new bioprosthesis was associated with improved outcomes or greater risk of bleeding. Methods and Results—We searched the PubMed database from the inception of these databases until April 2015 to identify original studies (observational studies or clinical trials) that assessed anticoagulation with warfarin in comparison with either aspirin or no antiplatelet or anticoagulant therapy. We included the studies if their outcomes included thromboembolism or stroke/transient ischemic attacks and bleeding events. Quality assessment was performed in accordance with the Newland Ottawa Scale, and random effects analysis was used to pool the data from the available studies. I2 testing was done to assess the heterogeneity of the included studies. After screening through 170 articles, a total of 13 studies (cases=6431; controls=18210) were included in the final analyses. The use of warfarin was associated with a significantly increased risk of overall bleeding (odds ratio, 1.96; 95% confidence interval, 1.25–3.08; P<0.0001) or bleeding risk at 3 months (odds ratio, 1.92; 95% confidence interval, 1.10–3.34; P<0.0001) compared with aspirin or placebo. With regard to composite primary outcome variables (risk of venous thromboembolism, stroke, or transient ischemic attack) at 3 months, no significant difference was seen with warfarin (odds ratio, 1.13; 95% confidence interval, 0.82–1.56; P=0.67). Moreover, anticoagulation was also not shown to improve outcomes at time interval >3 months (odds ratio, 1.12; 95% confidence interval, 0.80–1.58; P=0.79). Conclusions—Contrary to the current guidelines, a meta-analysis of previous studies suggests that anticoagulation in the setting of an aortic bioprosthesis significantly increases bleeding risk without a favorable effect on thromboembolic events. Larger, randomized controlled studies should be performed to further guide this clinical practice.

Dose of Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers and Outcomes in Heart Failure: A Meta-Analysis

Background The association between angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) doses on outcomes in patients with heart failure (HF) with reduced ejection fraction is uncertain. The objective of this study was to investigate the effect of dose of ACEI and ARBs on outcomes and drug discontinuation in patients with HF with reduced ejection fraction. Methods and Results MEDLINE, Ovid SP, and Embase were searched from the inception of these databases till August 2016. Randomized controlled trials that compared high doses of ACEI or ARB against low doses among patients with HF with reduced ejection fraction were included. Pooled analysis was done using a random-effects model, and quality of the studies was assessed by JADAD scale. The main outcomes were all-cause mortality and drug discontinuation. A total of 6 studies (4841 patients in low-dose and 4330 patients in high-dose groups) were included. Compared with low dose, high-dose ACEI or ARBs decreased all-cause mortality modestly (relative risk, 0.94; 95% confidence interval (CI), 0.89–1.00; P=0.05; I2=0%) and composite of HF hospitalizations and all-cause mortality (relative risk, 0.93; 95% CI, 0.87–1.00; P=0.04; I2=39.8%). No significant difference was found between the 2 groups in HF hospitalizations (relative risk, 0.94; 95% CI, 0.70–1.26; P=0.68; I2=52.8%) and all-cause hospitalizations (relative risk, 0.97; 95% CI, 0.85–1.11; P=0.67; I2=31.7%) risk. Discontinuation rates were also not significantly different in both groups (odds ratio, 1.13; 95% CI, 0.92–1.39; P=0.25; I2=32.6%). Conclusions In patients with HF with reduced ejection fraction, compared with lower doses, higher doses of ACEI and ARB significantly though modestly improved the composite end point of all-cause mortality or HF hospitalization without significantly increasing the chances of discontinuation.

Leadless pacemakers: A new era in cardiac pacing

Cardiac pacemakers are a critical management option for patients with rhythm disorders. Current efforts to develop leadless pacemakers have two primary goals: to reduce lead-associated post-procedural morbidity and to avoid the surgical scar associated with placement. After extensive studies on animal models and technological advancements, these devices are currently under investigation for human use. Herein, we review the evidence from animal studies and the technological advancements that have ushered in the era of use in humans. We also discuss different leadless pacemakers currently under investigation, along with limitations and future developments of this innovative concept.

Impact of statins on risk and survival of ovarian cancer

To the editor: While statins have been clearly shown to decrease mortality and morbidity in cardiovascular diseases, the role of statins as an anti-cancer agent is less well defined. Predicted through new guidelines published by American College of Cardiology, it is said that around 30% of Americans in the age group 40 to 75 will be using statins even if they do not have cardiovascular disease [1]. Recently, statins beneficial effect on cancer survival has also been highlighted in many studies. A Danish study [2] reported that people who have used statins have 20% lower chance of cancer deaths compared with those who have not used statins. Similarly studies have also shown that statins lower the incidence of common cancers such as breast, prostate and colorectal. This anticancer activity of statins is due to inhibition of isoprenoid biosynthesis which is essential for cancer growth and metastasis [3,4]. Ovarian cancer has the worst prognosis among gynecological cancers. It has been estimated that ovarian cancer causes approximately 15,000 deaths in USA annually [5]. Therefore, identification of protective factors and possible agents associated with increased survival can have great implications. Statins role in ovarian cancer has been controversial with varying opinions. In order to collect all the evidence, we conducted a literature search utilizing Medline (PubMed and Ovid) and Cochrane Library to identify studies related to statins effect on incidence and survival in ovarian cancer. Eight relevant citations were found and are summarized in Table 1. Only three studies [6,7,8] were found which reported the effect of statin therapy on ovarian cancer survival while the others [9,10,11,12,13] only reported risk of ovarian cancer. Table 1 Summary of the evidence regarding impact of statin therapy on risk and survival of ovarian cancer Habis et al. [6] reported a decrease in hazards of disease-specific death (adjusted hazard ratio, 0.23; p=0.04) among statin users in non-serous papillary epithelial ovarian cancer. Similarly Elmore et al. [7] showed significantly longer survival in statin users (62 months) compared with non-users (46 months, p=0.04). Out of the six studies [8,9,10,11,12,13] reporting risk of ovarian cancer, only one found a significant reduction in ovarian cancer incidence with statin usage. Baandrup et al. [9] documented a decrease risk only with respect to mucinous ovarian cancer enforcing the need for further subgroup analysis. When findings of five studies [8,10,11,12,13] were pooled in a meta-analysis conducted by Liu et al. [14], a significant 21% risk reduction was seen (relative risk [RR], 0.79; 95% confidence interval [CI], 0.64 to 0.98). The RR reduction was found to be 52% when long term statin usage was considered (RR, 0.48; 95% CI, 0.28 to 0.80). In conclusion, we suggest that statins impact on ovarian cancer warrants further investigation with larger randomized controlled trials as observational studies are subject to bias and may lead to false slight benefits. Effect of statins with respect to different histological subtypes also need to be further studied.

Prevalence of drug resistance associated mutations in Plasmodium vivax against sulphadoxine-pyrimethamine in southern Pakistan

BackgroundIn Pakistan, Plasmodium vivax and Plasmodium falciparum co-exist and usage of sulphadoxine-pyrimethamine (SP) against P. falciparum exposes P. vivax to the drug leading to generation of resistant alleles. The main aim of this study was to investigate frequency distribution of drug resistance associated mutations in pvdhfr, pvdhps genes and provide baseline molecular epidemiological data on SP-associated resistance in P. vivax from southern Pakistan.MethodsFrom January 2008 to May 2009, a total of 150 samples were collected from patients tested slide-positive for P. vivax, at the Aga Khan University Hospital, Karachi, or its collection units located in Baluchistan and Sindh Province. Nested PCR using pvdhfr and pvdhps specific primers was performed for all samples.91.3% (137/150) of the samples were tested PCR positive of which 87.3% (131/137) were successfully sequenced. Sample sequencing data was analysed and compared against wild type reference sequences.ResultsIn dhfr, mutations were observed at codons F57L, S58R and S117N/T. Novel non-synonymous mutations were observed at codon positions N50I, G114R and E119K while a synonymous mutation was observed at codon position 69Y. In dhps, mutations were observed at codon position A383G and A553G while novel non-synonymous mutations were observed at codon positions S373T, E380K, P384L, N389T, V392D, T393P, D459A, M601I, A651D and A661V.ConclusionThis is the first report from southern Pakistan on SP resistance in clinical isolates of P. vivax. Results from this study confirm that diverse drug resistant alleles are circulating within this region.

Renin–angiotensin blockade in heart failure with preserved ejection fraction: a systematic review and meta-analysis

Studies with angiotensin‐converting enzyme inhibitors (ACE‐Is) and angiotensin receptor blockers (ARBs) in patients with heart failure with preserved ejection fraction (HFpEF) have yielded inconsistent results. To conduct a systematic review and meta‐analysis of all evidence for ACE‐I and ARBs in patients with HFpEF, we searched PubMed, Ovid SP, Embase, and Cochrane database to identify randomized trials and observational studies that compared ACE‐I or ARBs against placebo or standard therapy in HFpEF patients. Random‐effect models were used to pool the data, and I2 testing was performed to assess the heterogeneity of the included studies. A total of 13 studies (treatment arm = 8676 and control arm = 8608) were analysed. Pooled analysis of randomized trials for ACE‐I and ARBs (n = 6) did not show any effect on all‐cause mortality [relative risk (RR) = 1.02, 95% confidence interval (CI) = 0.93–1.11, P = 0.68, I2 = 0%], while results from observational studies showed a significant improvement (RR = 0.91, 95% CI = 0.87–0.95, P = 0.005, I2 = 81.5%). In pooled analyses of all studies, ACE‐I showed a reduction of all‐cause mortality (RR = 0.91, 95% CI = 0.87–0.95, P = 0.01). There was no reduction in cardiovascular mortality seen, but in pooled analysis of randomized trials, there was a trend towards reduced HF hospitalization risk (RR = 0.91, 95% CI = 0.83–1.01, I2 = 0%, P = 0.074). These data suggest that ACE‐I and ARBs may have a role in improving outcomes of patients with HFpEF, underscoring the need for future research with careful patient selection, and trial design and conduct.

Sociodemographic Pattern of Depression in Urban Settlement of Karachi, Pakistan.

INTRODUCTION Depression is a global issue prevalent among developing countries like Pakistan as compared to developed countries. We conducted a study to assess the prevalence and identify the significant predictors of depression in an elite urban settlement in Karachi, Pakistan. MATERIALS AND METHODS This cross-sectional study was done in the elitist residential area of Karachi; Defence Housing Authority (DHA). Four hundred and twenty three participants were included by going to their residences. Self-administered questionnaires were handed out after taking informed consent. Level of depression was assessed by Patient Health Questionnaire (PHQ-9). Data were entered and analysed in Predictive Analytical Software v. 18.0. RESULTS The mean and median total score of the scale were 5.9 ± 5.4 and 4 (7) respectively with minimum score 0 and maximum 27. In this sequence, 139 (32.86%) respondents were identified to be depressed. It was found that females were slight more depressed than males (p = 0.063). Regression Model identified only gender and marital status as significant predictors of depression. Having a female gender increased 0.658 times chance of being depressed (p = 0.047). Unmarried person had 0.296 times more likely to be depressed (p = 0.019). Boredom was considered as significant factor of depression by the participants (p< 0.0001). Odds ratio signified depression occurred 0.310 times more if one was bored. DISCUSSION Depression should be considered as a major public health issue for the city. Public awareness should be done in all parts of the city in an attempt to reduce depression especially among the female gender.