A new modified biased estimator for Zero inflated Poisson regression model.

Zero-inflated Poisson (ZIP) model is widely used for counting data with excessive zeroes. The multicollinearity is the common factor in the explanatory variables of the count data. In this context, typically, maximum likelihood estimation (MLE) generates unsatisfactory results due to inflation of mean square error (MSE). In the solution of this problem usually, ridge parameters are used. In this study, we proposed a new modified zero-inflated Poisson ridge regression model to reduce the problem of multicollinearity. We experimented within the context of a specified simulation strategy and recorded the behavior of proposed estimators. We also apply our proposed estimator to the real-life data set and explore how our proposed estimators perform well in the presence of multicollinearity with the help of ZIP model for count data.

Influence Diagnostic Methods in the Poisson Regression Model with the Liu Estimator.

There is a long history of interest in modeling Poisson regression in different fields of study. The focus of this work is on handling the issues that occur after modeling the count data. For the prediction and analysis of count data, it is valuable to study the factors that influence the performance of the model and the decision based on the analysis of that model. In regression analysis, multicollinearity and influential observations separately and jointly affect the model estimation and inferences. In this article, we focused on multicollinearity and influential observations simultaneously. To evaluate the reliability and quality of regression estimates and to overcome the problems in model fitting, we proposed new diagnostic methods based on Sherman-Morrison Woodbury (SMW) theorem to detect the influential observations using approximate deletion formulas for the Poisson regression model with the Liu estimator. A Monte Carlo method is done for the assessment of the proposed diagnostic methods. Real data are also considered for the evaluation of the proposed methods. Results show the superiority of the proposed diagnostic methods in detecting unusual observations in the presence of multicollinearity compared to the traditional maximum likelihood estimation method.

Pleiotropic ameliorative effects of ellagitannin geraniin against metabolic syndrome induced by high-fat diet in rats.

OBJECTIVES: Metabolic syndrome (MetS), a multiplex risk factor for cardiovascular disease and type 2 diabetes, is increasingly prevalent worldwide. Ellagitannin geraniin, a polyphenol found in the rind of rambutan (Nephelium lappaceum), has demonstrated therapeutic effects against metabolism dysfunction. The aim of this study was to characterize the metabolic effects and possible mechanism of geraniin in rats with MetS induced by a high-fat diet (HFD). METHODS: MetS was induced in Sprague Dawley rats on an HFD, followed by a daily oral gavage of geraniin (25 mg/kg) for 4 wk. The outcomes of geraniin-treated rats were compared with those of untreated rats on either a control diet or an HFD and with rats with MetS treated with metformin on a daily basis (200 mg/kg). RESULTS: The supplementation of geraniin ameliorated multiple metabolic abnormalities caused by HFD, including hypertension, impaired glucose and lipid metabolism, ectopic fat deposition in the visceral fat and liver, and disturbed antioxidant mechanism and inflammatory response. The benefits conferred by geraniin were comparable to metformin. Transcriptomic analysis revealed a profound influence of geraniin on the hepatic expression profiles. The lipid and steroid metabolic processes that were aberrantly activated by HFD were suppressed by geraniin. Based on the differential transcriptomes, geraniin also exerted a significant modulatory effect on the expression of mitochondrial genes, potentially influencing the mitochondrial activity and leading to the observed beneficial effects. CONCLUSION: Geraniin supplementation mitigated metabolic anomalies of MetS in rats, making it an attractive drug candidate for further investigation.

Direct true lumen versus conventional cannulation for acute type-A aortic dissection.

Acute type-A aortic dissection is a surgical emergency and has a high rate of short-term mortality. Aortic dissection is highly under-reported in Pakistan. With the technological developments in its management, arterial cannulation technique of direct true lumen cannulation has emerged with improved outcomes. We aimed to compare the mortality and morbidity outcomes between direct true lumen and conventional cannulation techniques for arterial access in patients with acute type- A aortic dissection under a single-centre retrospective review from 2007 to 2017. Mean age of the participants was 43.3±11.6 vs 45±12.4 years with males being dominant in both groups. Frequency of overall morbidity was high in conventional cannulation group (Group-B), though it did not attain statistical significance, (p>0.999). Mortality rate was also high in Group-B (10% vs 30%), (p=0.582). Direct true lumen cannulation is an equally reliable option for establishing cardiopulmonary bypass due to reduced mortality and morbidity and may be given preference when dissection is extending into femoral and innominate arteries.

Anomalous origin of the left coronary artery from the pulmonary artery: A surgical certainty.

This study aims to assess the clinical presentation and the outcomes of a surgical correction of an anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA). A retrospective review was carried out on the charts of six patients admitted for ALCAPA surgery at Aga Khan University Hospital, Karachi from March 2017 to May 2018.Dyspnoea, palpitation, poor feeding, fatiguability, pallor and a murmur of mitral regurgitation were the main presenting features. The pre-operative median left ventricular ejection fraction (LVEF) was 64%. Coronary reimplantation was performed in all the patients with a mitral valve repair being done in only one patient. The mea n LV EF was 66 .3%,p ost- ope rativel y. Mitra l regurgitation (MR) improved in patients post-operatively with trace in 2 patients and mild MR in one. Surgical correction by coronary re-implantation yields favourable outcomes in ALCAPA and significantly reduces the morbidity and mortality rates associated with the disease.

Effect of steroids on inflammatory markers and clinical parameters in congenital open heart surgery: a randomised controlled trial.

BACKGROUND: Cardiopulmonary bypass is associated with systemic inflammatory response. Steroids suppress this response, although the therapeutic evidence remains controversial. We hypothesised that intravenous steroids in children undergoing open-heart surgery would decrease inflammation leading to better early post-operative outcomes. We conducted a randomised controlled trial to evaluate the trends in the levels of immunomodulators and their effects on clinical parameters. OBJECTIVE: To assess the effects of intravenous steroids on early post-operative inflammatory markers and clinical parameters in children undergoing open-heart surgery. MATERIALS AND METHODS: A randomised controlled trial involving 152 patients, from one month up to 18 years of age, who underwent open-heart surgery for congenital heart disease from April 2010-2012 was carried out. Patients were randomised and administered either three scheduled intravenous pulse doses of dexamethasone (1 mg/kg) or placebo. Blood samples were drawn at four time intervals and serum levels of inflammatory cytokines - Interleukin-6, 8, 10, 18, and tumour necrosis factor-alpha - were measured. Clinical parameters were also assessed. RESULTS: Blood cytokine levels were compared between the dexamethasone (n=65) and placebo (n=64) groups. Interleukin-6 levels were lower at 6 and 24 hours post-operatively (p<0.001), and Interleukin-10 levels were higher 6 hours post-operatively (p<0.001) in the steroid group. Interleukin-8, 18, and tumour necrosis factor-alpha levels did not differ between the groups at any time intervals. The clinical parameters were similar in both the groups. CONCLUSION: Dexamethasone caused quantitative suppression of Interleukin-6 and increased Interleukin-10 activation, contributing to reduced immunopathology, but it did not translate into clinical benefit in the short term.

Report: Study is about the prevalence of the HCV disease and survival of HCV patients with associated factors in the population of district Multan.

To find out the significant factors associated with HCV disease and evaluate the impact of these factors on the survival pattern of HCV patients in district Multan. The study was conducted in Nishter Hospital of Multan district from 1st January 2011 to 1st October 2012. To see a significant difference between the survival rates of patients with associated factors, non-parametric Cox- proportional hazard model with their graphical results were used. All the patients above 11 years old of both sexes were included in the study. All those who were surviving with HCV disease were studied with their associated factors such as age, family history (FH) barber/parlor services, blood group (BG) types weight loss (WL), Gender and drug use were collected from Nishter Hospital Multan. Results indicated that age, blood group types and gender are the most significant factors in the patients who are surviving with HCV disease. It was also observed that survival rate of female patients is high as compare to male patients.

Tetralogy of Fallot with absent pulmonary valve syndrome; appropriate surgical strategies.

OBJECTIVE: To evaluate patients presenting with Tetralogy of Fallot with absent pulmonary valve syndrome to a tertiary care hospital and their surgical management. METHODS: The retrospective study was conducted at Congenital Cardiac Services, Aga Khan University Hospital, Karachi, Pakistan, and comprised data of Tetralogy of Fallot patients between April 2007 and June 2012. Data was analysed together with follow-up echocardiography. Variables assessed included demographics, imaging, operative technique, complications, post-operative recovery and follow-up echocardiography. SPSS 17 was used for statistical analysis. RESULTS: Of the 204 patients, 6 (3%) had undergone surgical correction for Tetralogy of Fallot with absent pulmonary valve syndrome. All 6(100%) patients underwent complete repair. Median age for surgery was 8.5 years (range: 0.5-29 years). Of the different surgical strategies used, Contegra and Bioprosthetic valve placement had satisfactory outcome with minimal gradient at Right Ventricular Outflow Tract, good ventricular function and mild valvular regurgitation. One (16.6%) patient with Trans Annular Patch developed post-operative Right Ventricle Outflow Tract gradient of 80mmHg with moderate pulmonary regurgitation. One (16.6%) patient with monocusp valve developed free pulmonary regurgitation at 6 months. The other 4(66.6%) patients are currently free from any complications or re-intervention. CONCLUSIONS: Early surgery is preferred in symptomatic patients. The repair depends upon achieving integrity of pulmonary circulation which is best achieved by using right ventricle to pulmonary artery conduit or inserting a pulmonary valve.

Intraoperative air embolism originating from a pulmonary vein.

Air embolism entering the systemic arterial system originating from the pulmonary circuit itself is an extremely rare occurrence. We report the case of an 18-year-old female undergoing correction of an atrial septal defect, who had an air embolism that is believed to have originated from the right superior pulmonary vein. Although the exact mechanism of air entry remains a matter of speculation, several plausible hypotheses are proposed and discussed. Injury to a pulmonary vein may lead to air entry with migration to the left atrium and ultimately to systemic embolism.

Transcatheter versus surgical closure of atrial septum defect: a debate from a developing country.

INTRODUCTION: This study compares the effectiveness and cost of trans-catheter verses surgical closure of secundum atrial septum defect (ASD). ASD accounts for 10% of congenital cardiac defects. Trans-catheter closure of secundum ASD is increasingly used as the primary intervention. Surgical repair is advised in a proportion of secundum type defects which are unsuitable for device closure. METHODS: We reviewed the clinical course of 176 patients who underwent closure of isolated secundum ASD. The patients were assigned to either the device or surgical group depending upon the treatment they received. Successful closure was assessed immediately after the procedure. The following outcomes were studied: mortality, morbidity, hospital stay, and costs. RESULTS: Ninety five patients were in the surgical group and 81 patients were in the group undergoing device closure. The median age was 14.0 years (range 1.1-61.0) for surgical group and 24.0 years (range 0.5-68.0) for the device group. The mortality in both groups was 0. The procedure success rate was 100% for the surgical group and 96.3% for the device group. The complication rate was 13.7% for surgical group and 7.4% for the device group. The mean length of hospital stay was 5.0 ± 2.7 days for surgical group and 3.0 ± 0.4 days for device group. The procedure cost for surgery was found to be 12.3% lower than that of trans-catheter closure. CONCLUSION: Successful closure is achieved by both methods. Trans-catheter closure results in lower rate of complication and hospital stay but the cost of the procedure tends to be higher than surgery.

Clinical outcomes of surgically corrected atrial septal defects.

OBJECTIVE: To examine the outcomes of surgical repair of atrial septal defects in paediatric and adult patients. METHODS: The retrospective study comprised data of 84 patients who had undergone surgical correction of atrial septal defect at the Aga Khan University Hospital, Karachi, between June 2006 and December 2011. All patients with isolated atrial septal defect (ostium secundum, ostium primum and sinus venosus with or without partial anomalous pulmonary venous connection) were included. Clinical and transthoracic echocardiographic data was reviewed. SPSS 17 was used for statistical analysis. RESULTS: There were no deaths in the study population. The mean time for follow-up was 6.5 +/- 9.9 months. Most of the patients (n = 80; 95.2%) were in NewYork Heart Association class I at follow-up, while the remaining 4 (4.8%) were in New York Heart Association class II. Post-operatively, 8 (9.5%) patients developed brief episodes of arrhythmias. There were 3 (3.57%) patients who were re-admitted within 30 days; 2 (66.7%) had superficial wound infection, while 1 (33.3%) had to be re-opened because of cardiac tamponade. CONCLUSION: Surgical repair of atrial septal defects is a safe procedure which is associated with excellent results and low morbidity.

Family-centered rounds in Pakistani pediatric intensive care settings: non-randomized pre- and post-study design.

BACKGROUND: Involvement of family in bedside rounds is one strategy to implement family-centered care to help families get clear information about their child, and be actively involved in decision-making about care. However in developing countries such as Pakistan, daily bedside rounds include the physician, residents, medical students and a nurse/technician. Parents are not currently a part of these rounds. OBJECTIVE: To assess whether family-centered rounds improve parents' and health care professionals' satisfaction, decrease patient length of stay, and improve time utilization when compared to traditional practice rounds in a population with a low literacy rate, socioeconomic status, and different cultural values and beliefs. DESIGN: A non-randomized before-after study design. SETTING: A private hospital in Karachi, Pakistan. PARTICIPANTS: A convenience sample of 82 parents, whose children were hospitalized for a minimum of 48h, and 25 health care professionals able to attend two consecutive rounds. METHODS: During the before phase, traditional bedside rounds were practiced; and during after phase, family-centered rounds were practiced. Parents and health care professionals completed a questionnaire on the second day of rounds. An observational form facilitated data collection on length of stay and time utilization during. RESULTS: Parents' ratings during the family-centered rounds were significantly higher for some parental satisfaction items: evidence of team work (p=0.007), use of simple language during the rounds (p=0.002), feeling of inclusion in discussion at rounds (p=0.03), decision making (p=0.01), and preference for family-centered rounds (p=<0.001). No significant differences were found in health care professionals' satisfaction between rounds. Patient length of stay was significantly reduced in the family-centered rounds group, while no significant difference was found in the duration of rounds. Family-centered rounds served as an opportunity for parents to correct/add to patient history or documentation. CONCLUSION: Parents were satisfied with both forms of rounds; however, they appeared to have a greater preference for family-centered rounds than health care professionals. Family-centered rounds were a resource for Pakistani parents, enabling direct communication with the medical team without impacting on the time required to complete rounds. Family-centered rounds may improve quality of care such as decreasing length of stay or preventing critical incidents.

Successful surgical intervention of total anomalous pulmonary venous drainage in the third decade of life.

Total anomalous pulmonary venous drainage (TAPVD) accounts for approximately 1.5% of all congenital heart diseases. It is usually diagnosed in the neonatal period and is rarely seen in adults. We report an unusual case of a patient with TAPVD who was successfully treated at the age of 28 years. We believe that this is the oldest person in the South Asian literature to undergo surgical correction of TAPVD.

Successful Repair of Complete Atrio-ventricular Septal Defect at the Beginning of the Second Decade.

Complete atrio-ventricular septal defects (CAVSD) are present in about 3% of children born with congenital heart pathologies. They usually require early surgical correction, mostly in infancy, and surgery is considered to be the gold standard. It is unlikely that anyone would survive beyond the first years without severe morbidity. However, we report a case of a Pakistani girl who underwent successful surgical repair of CAVSD at the age of 11.

Contegra valved conduit in the paediatric population: an exciting prospect for right ventricle to pulmonary artery reconstruction; experience and outcomes at Aga Khan University.

OBJECTIVE: The focus of this study is to share the experience and outcomes of Contegra graft implantation in the paediatric and adult population in Pakistan. METHODS: Between May 2007 and July 2011, 16 patients, underwent implantation of a Contegra valved conduit. All operations were performed through a median sternotomy with cardiopulmonary bypass. Indications included: Pulmonary atresia with ventricular septal defect (n = 11), Tetralogy of Fallot with absent Pulmonary Valve (PV) syndrome (n = 2), double outlet right ventricle, transposition of great arteries and pulmonary stenosis (n = 1), isolated aortic valve disease (n = 1) and a pseudo-aneurysm with infective endocarditis (n = 1).Conduit sizes varied between 16-22 mm. RESULTS: The three in hospital deaths were unrelated to the Contegra valved conduit. One patient was lost to follow up. Of the 12 survivors, 10 are currently free from re-operation or complications related to the conduit while one needed distal pulmonary artery dilatation owing to critical stenosis and another had severe Valvular regurgitation. Echocardiographic evaluation of the Contegra valved conduit demonstrated no haemodynamically significant valve regurgitation in 10 patients. CONCLUSION: In this small review of 16 operations using the Contegra valved conduit for Right Venticular Outflow Tract (RVOT) reconstruction in the paediatric population, we observed good post operative results concerning conduit function. The Contegra conduit provides an excellent substitute to the homograft with satisfactory early and mid-term results though long-term results are awaited in Pakistan.

Earlier surgical intervention in congenital heart disease results in better outcome and resource utilization.

BACKGROUND: Congenital heart disease (CHD) accounts for a major proportion of disease in the pediatric age group. The objective of the study was to estimate the cost of illness associated with CHD pre, intra and postoperatively; among patients referred to a tertiary care hospital in Karachi, Pakistan. This is the first study conducted to estimate the cost of managing CHD in Pakistan. METHODS: A prevalence based cost of illness study design was used to estimate the cost of cardiac surgery (corrective & palliative) for congenital heart defects in children ≤ 5 years of age from June 2006 to June 2009. A total of 120 patients were enrolled after obtaining an informed consent and the data was collected using a pre-tested questionnaire. RESULTS: The mean age at the time of surgery in group A (1-12 mo age) was 6.08 ± 2.80 months and in group B (1-5 yrs) was 37.10 ± 19.94 months. The cost of surgical admission was found to be significantly higher in the older group, p = 0.001. The total number and cost of post-operative outpatient visits was also higher in group B, p = 0.003. Pre and post operative hospital admissions were not found to be significantly different among the two groups, p = 0.166 and 0.627, respectively. The number of complications were found to be different between the two groups (p = 0.019). Majority of these were contributed by hemorrhage and post-operative seizures. CONCLUSION: This study concluded that significant expenditure is incurred by people with CHD; with the implication that resources could be saved by earlier detection and awareness campaigns.

Dual chamber pacemaker implants--a new opportunity in Pakistan for children with congenital and acquired complete heart block.

Implantation of cardiac pacemakers has been practiced for at least five decades with continuous developments of the hardware. The invention of dual chamber pacemakers has initiated a debate concerning its superiority over single chamber ventricular pacemakers. Throughout the world, surgeons have been using dual chambered permanent pacemakers with successful follow ups. However, Pakistan has not yet taken the advantage of such pacemaker devices till now. We report three cases that underwent a dual chamber permanent pacemaker implantation for the first time in children less than 8 kg with successful follow ups.

Surgical correction of aorto-pulmonary window: a rare and lethal cause of pulmonary hypertension.

Aorto-pulmonary window is a relatively rare congenital cardiac malformation with an overall incidence of 0.1%. Pulmonary hypertension develops quickly if the lesion is left untreated hence early surgical intervention is warranted after diagnosis. The surgery for correction of APW has evolved over years, currently an open repair on cardiopulmonary bypass (CPB) with a single patch technique yields good results. Mortality is affected by association of pulmonary hypertension and other cardiac malformations. We present a case of an infant with a large type II APW with a relatively low pulmonary vascular resistance. Hospital stay was complicated because of pulmonary arterial disease making it an important reason for correction in the first few months of life.

Is early correction of congenital ventricular septal defect a better option in a developing country?

OBJECTIVE: To assess and evaluate the effectiveness of early ventricular septal defect (VSD) repair in a developing country by comparing the outcomes in two age groups. METHODS: A total of 39 patients underwent VSD repair at a tertiary care hospital in Karachi over a period of 2.5 years. Patients were divided into Group 1 (<2 years) and Group 2 (2-18 yrs). Perioperative and postoperative variables were reviewed retrospectively for each patient and compared with the development of complications and the effect on postoperative recovery times. The data was analyzed using Mann Whitney test for continuous variables and Fischer's exact test for categorical variables. RESULTS: Mean age at surgery was 10.1 +/- 7.0 months and 108.5 +/- 54.0 months for both groups, respectively. Two patients died. Procedure time was not affected by decreasing age (p = 0.622) but Cardio pulmonary Bypass duration (p = 0.040) and Aortic Cross Clamp time (p = 0.063) were significantly affected. No associated significance was obtained when hospital stay (p = 0.085) was observed. Increased duration of ventilation (p = 0.000) and length of ICU stay (p = 0.003) were highly significant for the younger age group. Presence of residual VSD (p = 0.025) was also significantly affected by lower age. There was no significant difference in the number of patients with complications (p = 1.000) among the 2 groups. CONCLUSION: Age does not increase morbidity rates after VSD repair although postoperative recovery times are increased with decreasing age. Hence, there is no justification in delaying VSD repair.