Use of appropriate statistical tools in biomedical research: Current trend & status

Background & objectives: Due to lack of appropriate statistical knowledge, published research articles contain various errors related to the design, analysis and interpretation of results in the area of biomedical research. If research contains statistical error, however, costly, it may be of no use and the purpose of the investigation gets defeated. Many biomedical research articles published in different peer reviewed journals may retain several statistical errors and flaws in them. This study aimed to examine the trend and status of application of statistics in biomedical research articles. Study design, sample size estimation and statistical measures are crucial components of a study. These points were evaluated in published original research articles to understand the use or misuse of statistical tools. Methods: Three hundred original research articles from the latest issues of selected 37 journals were reviewed. These journals were from the five internationally recognized publication groups (CLINICAL KEY, BMJ Group, WILEY, CAMBRIDGE and OXFORD) accessible through the online library of SGPGI, Lucknow, India. Results: Among articles assessed under present investigation, 85.3 per cent (n=256) were observational, and 14.7 per cent (n=44) were interventional studies. In 93 per cent (n=279) of research articles, sample size estimation was not reproducible. The simple random sampling was encountered rarely in biomedical studies even though none of the articles was adjusted by design effect and, only five articles had used randomized test. The testing of assumption of normality was mentioned in only four studies before applying parametric tests. Interpretation & conclusions: In order to present biomedical research results with reliable and precise estimates based on data, the role of engaging statistical experts need to be appreciated. Journals must have standard rules for reporting study design, sample size and data analysis tools. Careful attention is needed while applying any statistical procedure as, it will not only help readers to trust in the published articles, but also rely on the inferences the published articles draw.

Study of Surgical Infection in a Tertiary Care Hospital

Introduction: Surgical site infection is a common postoperative problem causing significant post-operativemorbidity and mortality, prolonged indoor stay and addsbetween 10% and 20% to hospital cost. In India, rate ofsurgical site infections in various set-ups had been reportedto be 4.2-21%. Current study aimed to record the incidenceof surgical site infection in present set up in both elective andemergency cases and to assess the possible risk factors andanalyze the measures to prevent surgical site infection.Material and Methods: The present prospective study wasconducted in the post graduate Department of General Surgery,Rohilkhand Medical College, Bareilly, from 1 November 2017to 31 October 2018 to determine the incidence of surgical siteinfections and to assess the risk factors associated with thesurgical site infections. Samples were processed for microbialflora and antibiotic sensitivity.Results: Incidence of surgical site infections in present studywas 13%. In elective surgeries it was 7.1% while in emergencysurgeries it was 26.7%. Incidence was higher in patients withdiabetes, smokers and obese patients. Highest incidence waspresent in dirty wounds. Incidence was lower in patientswho have shorter pre operative hospital stay and underwentsurgery for shorter duration. In most of the cases surgical siteinfections occured on post-operative day 7. Patients with SSIhad longer mean duration of hospital stay as compared tothose who did not have SSI. Staphylococcus aureus was themost common organism isolated followed by E. Coli.Conclusion: We reported a significant association of SSIwith type of procedure (open and emergency), diabetes,obesity, smoking, duration of preoperative hospital stays,ASA physical grade, duration of surgery, duration of drainsand type of wound according to wound classification.

Antiplasmodial activity of silver nanoparticles: A novel green synthesis approach

Objective: To synthesize silver nanoparticles using silver nitrate by a green technique which involves different compositions of aqueous leaf extracts of Azadirachta indica (neem) and Ocimum sanctum (tulsi). Methods: Their shape and size were determined using transmission electron microscopy and UV-visible spectroscopy. Their antiplasmodial activity was studied using the malarial parasite strain (Plasmodium falciparum, 3D7). The parasite strain (3D7) was col ected and revived in vitro using Trager and Jensen method in RPMI 1640 medium for 7-8 cycles. Half maximal effective concentration values were calculated by nonlinear regression analysis. Results: Transmission electron microscopy results confirmed the formation of silver nanoparticles with size ranging from 4.74-39.32 nm and their size differs by varying the concentrationsfrom20％to100％ofneemextractinneemandtulsiextracts.Itwasobservedthat samples B and C showed half maximum effective concentration of about 0.3μM. Conclusions:It can be easily established that the aqueous leaf extracts of neem and tulsi in combination can be a good source for synthesis of silver nanoparticles with smal size possessing appreciable antiplasmodial activity.

Prophylactic gabapentin for prevention of postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy: a randomized, double-blind, placebo-controlled study.

BACKGROUND: Gabapentin is an antiepileptic drug. Its antiemetic effect is demonstrated in chemotherapy-induced acute and delayed onset of nausea and vomiting in breast cancer patients. AIM: To evaluate the antiemetic effect of gabapentin on incidence and severity of postoperative nausea and vomiting in laparoscopic cholecystectomy. SETTINGS AND DESIGN: Double-blind, randomized, placebo-controlled study. MATERIALS AND METHODS: Two hundred and fifty patients of ASA physical status I and II, scheduled for laparoscopic cholecystectomy were randomly assigned into two equal groups to receive 600 mg gabapentin or matching placebo two hours before surgery. Standard anaesthesia technique was used. Fentanyl was used as rescue postoperative analgesic. Ondansetron 4 mg was used intravenously as rescue medication for emesis. The total number of patients who had nausea or vomiting, and its severity and total fentanyl consumption in the first 24 hours were recorded. STATISTICAL ANALYSIS: "Z test" was used to test the significance of severity of post-operative nausea and vomiting between groups. Fentanyl consumed in each group (Mean+/-SD) within 24 hrs was compared using student t test. P value < 0.05 was considered significant. RESULTS: There were no demographic difference between the two groups. Incidence of post-operative nausea and vomiting within 24 hrs after laparoscopic cholecystectomy was significantly lower in gabapentin group (46/125) than in the placebo group (75/125) (37.8% vs 60%; P =0.04). There was a significantly decreased fentanyl consumption in gabapentin group (221.2+/-92.4 microg) as compared to placebo group (505.9+/-82.0 microg; P =0.01). CONCLUSION: Gabapentin effectively suppresses nausea and vomiting in laparoscopic cholecystectomy and post-operative rescue analgesic requirement.

A tertiary care hospital-based study of conventional risk factors including lipid profile in proven coronary artery disease.

BACKGROUND: The prevalence and mortality rates of coronary artery disease have been known to be higher in the Indian than the Western population. Most data on lipid levels in Indians have been obtained from studies on migrant Asian Indians. There are insufficient data on lipid profile and other conventional risk factors in Indian patients living within India. METHODS AND RESULTS: The study included 2656 consecutive patients who underwent coronary angiography between March 1998 and February 2002. Of these, 2399 subjects had angiographically proven coronary artery disease (group 1) while 257 had normal coronary arteries (group 2). Lipid values were measured in the fasting state on the morning the coronary angiography was done. Patients receiving lipid-lowering agents, those having renal, hepatic or thyroid disorders, patients presenting within 8 weeks after acute myocardial infarction, and patients who were taking noncardiac drugs that affect the lipid profile were excluded from the study. Other conventional risk factors were also recorded. In subjects with coronary artery disease and normal coronary arteries, the levels of mean total cholesterol recorded were 178.5+/-42.1 mg/dl v. 154.1+/-40.2 mg/dl (p<0.001), high-density lipoprotein cholesterol 30.6+/-9 mg/dl v. 27.3+/-6.8 mg/dl (p<0.001), low-density lipoprotein cholesterol 109.8+/-35.4 mg/dl v 93.6+/-33.9 mg/dl (p<0.001), and triglyceride 190.7+/-95.4 mg/dl v. 157.6+/-73.5 mg/dl (p<0.001), respectively. In subgroup analysis by age, the younger coronary artery disease group (< or = 40 years) had significantly higher total and low-density lipoprotein cholesterol levels than the older group (> 40 years), viz. 194.6+/-51.4 mg/dl v. 176.3+/-40.2 mg/dl (p<0.001), and 118.3+/-39.6 mg/dl v. 108.7+/-36.1 mg/dl (p=0.001). Triglyceride levels were not significantly different [211.7+/-105.1 mg/dl v. 187.8+/-93.6 mg/dl (p=ns)], being equally high in both subgroups and, although high-density lipoprotein cholesterol levels were different, this difference was minimal, being equally low in both [32.7+/-9.5 mg/dl v. 30.3+/-9.0 mg/dl (p=ns)]. In the subgroup analysis of those with coronary artery disease, diabetics had significantly lower total cholesterol [174+/-41.1 mg/dl v. 180.4+/-42.4 mg/dl (p<0.001)] and low-density lipoprotein cholesterol levels [105.8+/-34 mg/dl v. 111.5+/-35.8 mg/dl (p<0.001)] than non-diabetics, whereas triglyceride and high-density lipoprotein cholesterol levels were not significantly different, triglycerides being equally high in both [186.2+/-95.5 mg/dl v. 192.5+/-95.2 mg/dl (p=ns)], and high-density lipoprotein equally low in both [30.9+/-9.3 mg/dl v. 30.5+/-9 mg/dl (p=ns)]. The commonest associated conventional risk factor in diabetics was hypertension and, in the younger age group (< or = 40 years), it was smoking and a positive family history of premature coronary artery disease. CONCLUSIONS: We conclude that in north Indians, coronary artery disease occurs at much lower levels of total cholesterol and low-density lipoprotein cholesterol than other populations, and high triglyceride and low high-density lipoprotein levels are more of a universal phenomenon in this population. Younger patients have a more atherogenic lipid profile than the older subgroup with coronary artery disease, and smoking and a family history of premature coronary artery disease are the most common associated risk factors. Total cholesterol levels seem to play a lesser role in the occurrence of coronary artery disease in diabetics, the presence of which is in itself overwhelming for the occurrence of coronary artery disease.

Bronchobiliary fistula: an anaesthetic point of view.

Bronchobiliary fistula is defined as the passage of bile in the bronchi and in the sputum (bilioptysis). This rare disorder is associated with significant morbidity. Authors review the anaesthetic management of bronchobiliary fistula and recommend the use of double lumen endotracheal tube even in cases with a closed/sealed bronchobiliary fistula.

Drug sensitivity assay for leukaemic cells by flow cytometry.

BACKGROUND & OBJECTIVES: Drug sensitivity assays are useful in oncology practice for evaluating the sensitivity of malignant cells to anti-cancer drugs. The usefulness of such assays for the prediction of clinical response to therapy has also been demonstrated. The existing methods used for this purpose are time consuming and labour intensive. Here we report a simplified flow cytometry based assay for evaluating the in vitro drug sensitivity of leukaemic cells. METHODS: The chemo-sensitivity of three human leukaemic cell lines (a lymphoblastoid cell line, Jurkat; an erythroleukaemic cell line, K 562 and a myelomonocytic cell line HL-60) was investigated by flow cytometry. Flow cytometry was used to determine LD50 (50% inhibitory concentration) for prednisolone on Jurkat and daunorubicin on HL 60 and K 562 cell lines respectively. Per cent cell death could directly be assessed on a flow cytometer by measuring the fluorescence after staining with propidium iodide (PI). For comparison MTT assay was also performed using prednisolone on Jurkat and daunorubicin on HL-60. RESULTS: Cytotoxic effect of drugs was found to be dose dependent. Mean LD50 of prednisolone for Jurkat cells by flow cytometry was 0.805 +/- 0.058 mg/ml and by MTT assay 0.866 +/- 0.115 mg/ml. Mean LD50 of daunorubicin for HL-60 was 1.96 +/- 0.05 micrograms/ml by flow cytometry and 1.90 +/- 0.282 micrograms/ml by MTT assay. The mean LD50 of daunorubicin to K 562 was 0.49 +/- 0.049 mg/ml by the flow cytometry method. The inter-assay variation for the LD50 by flow cytometry based assay was found to be 6, 14 and 10 per cent for Jurkat, HL-60 and K 562 respectively. INTERPRETATION & CONCLUSION: We report a flow cytometry based drug-sensitivity assay for leukaemic cells, which uses a single dye staining and is rapid, technically simple and reproducible. The results compare well with the more commonly used MTT assay, which is labour intensive and time consuming. The limitation of our method is that it can only be used for studying cells in suspension and is therefore not suitable for adherent cell lines.

Hepatorenal syndrome: pathophysiology and treatment.

The hepatorenal syndrome (HRS) is a unique form of acute renal failure with entirely normal renal histology in advanced liver disease. Its diagnosis is made by exclusion of all causes of renal failure and by all the five major criteria as set by the International Ascites Club. The presence of hepatomegaly, poor nutritional status, and oesophageal varices at endoscopy are associated with a high risk of HRS. The liver tests, the Child-Pugh score, are of no value in prediction of its occurrence. Contraction of the effective blood volume, which may lead to renal hypoperfusion with preferential renal cortical ischaemia, is proposed pathogenesis of the condition. Because understanding of the pathogenesis of HRS is incomplete, therapy is supportive only. Optimal fluid management is vital as there is almost invariably a reduction in effective arterial blood volume. Dopamine, frusemide and haemofiltration may be helpful in management of fluid overload but do not affect renal function. TIPS has been used successfully in small series of patients. The vasopressin analog also has been used with early excellent response. The treatment of HRS has been discouraging and the only proven cure for HRS is liver transplantation at this point of time.

Congenital intracranial teratoma of the lateral ventricle.

A case of lateral ventricular teratoma in neonate, where near total excision of tumour was done, is being reported with the review of literature.

Quantitative structure-activity relationship studies on some anticancerous, antiviral and cytostatic agents.

QSAR studies using molecular connectivity and van der Waal volume have been performed on a new series of hydroxyguanidine derivatives and a series of isoindolediones. Regression analysis has shown that anticancer and antiviral activity of hydroxyguanidines as well as cytostatic activity of isoindolediones correlate well with both the structural parameters.

Quantitative structure activity relationship studies on 3-triazines using van der Waal volume and molecular connectivity index.

QSAR studies have been performed on the homologues of 3-triazines, using molecular connectivity index and van der Waal volume as structural parameters. The regression analysis has shown good correlation between antitumour activity and the two structural parameters.