Application of student's t-test, analysis of variance, and covariance

Student's t test (t test), analysis of variance (ANOVA), and analysis of covariance (ANCOVA) are statistical methods used in the testing of hypothesis for comparison of means between the groups. The Student's t test is used to compare the means between two groups, whereas ANOVA is used to compare the means among three or more groups. In ANOVA, first gets a common P value. A significant P value of the ANOVA test indicates for at least one pair, between which the mean difference was statistically significant. To identify that significant pair(s), we use multiple comparisons. In ANOVA, when using one categorical independent variable, it is called one-way ANOVA, whereas for two categorical independent variables, it is called two-way ANOVA. When using at least one covariate to adjust with dependent variable, ANOVA becomes ANCOVA. When the size of the sample is small, mean is very much affected by the outliers, so it is necessary to keep sufficient sample size while using these methods.

Selection of appropriate statistical methods for data analysis

In biostatistics, for each of the specific situation, statistical methods are available for analysis and interpretation of the data. To select the appropriate statistical method, one need to know the assumption and conditions of the statistical methods, so that proper statistical method can be selected for data analysis. Two main statistical methods are used in data analysis: descriptive statistics, which summarizes data using indexes such as mean and median and another is inferential statistics, which draw conclusions from data using statistical tests such as student's t-test. Selection of appropriate statistical method depends on the following three things: Aim and objective of the study, Type and distribution of the data used, and Nature of the observations (paired/unpaired). All type of statistical methods that are used to compare the means are called parametric while statistical methods used to compare other than means (ex-median/mean ranks/proportions) are called nonparametric methods. In the present article, we have discussed the parametric and non-parametric methods, their assumptions, and how to select appropriate statistical methods for analysis and interpretation of the biomedical data.

Descriptive statistics and normality tests for statistical data

Descriptive statistics are an important part of biomedical research which is used to describe the basic features of the data in the study. They provide simple summaries about the sample and the measures. Measures of the central tendency and dispersion are used to describe the quantitative data. For the continuous data, test of the normality is an important step for deciding the measures of central tendency and statistical methods for data analysis. When our data follow normal distribution, parametric tests otherwise nonparametric methods are used to compare the groups. There are different methods used to test the normality of data, including numerical and visual methods, and each method has its own advantages and disadvantages. In the present study, we have discussed the summary measures and methods used to test the normality of the data.

Management of Appendicular Lump: Early exploration Vs conservative management.

Background: Acute appendicitis is one of the most common acute surgical condition of the abdomen and appendicular lump is formed if treatment is delayed. It is encountered in 2 – 6%of patients. The traditional treatment of appendicular lump is conservative followed by delayed appendectomy. During conservative treatment 10-20% are not resolved and lead to gangrene or perforation followed by localized abscess or generalized peritonitis requiring early surgical intervention. Aims & Objective: A comparison of early exploration versus conservative management of appendicular lump. Material and Methods: A total of 632 patients were admitted in emergency and OPD of this hospital with diagnosis of appendicular lump and acute appendicitis over a period of three years, all were included in the study. All age groups and both sexes were included. The patients were divided randomly into two groups. Group I, early surgical exploration and group II, conservative approach with OCHSNER SHERREN, REGIME followed by interval appendectomy. Results: Out of 632 patients, only 62 patients who presented with appendicular lump were reviewed, suggesting 9.81% incidence. Maximum patients were found in age group of 21–30 years. Average duration of symptoms was 4 days. Two methods were adopted for the management of appendicular lump. The first group included 31 patients who were operated immediately after investigations and second group of 31 patients were managed conservatively followed by delayed appendectomy. In the first group mean hospitalization time was 4 days. Residual abscess, adhesive intestinal obstruction, failure of treatment and readmission were not observed. In the II group mean hospitalization time 10 days, more chances of residual abscess, adhesive intestinal obstruction, failure of treatment and readmissions were noted. Conclusion: Based on our finding, it can be concluded that early surgical exploration confirms the diagnosis and cures the problem, reduce the cost of management, shortens the convalescence and hospital stay with reasonably satisfactory outcome.

Profile of burn trauma in Rohilkhand region of Uttarpradesh.

Background: Burn trauma is the common problems seen in emergency in tertiary care centre of Rohilkhand region. So, far there is no published study regarding the magnitude of burn trauma in this area. Aims & Objective: To study the etiology of major burn trauma in Rohilkhand region of Uttar Pradesh. Material and Methods: This retrospective study was carried out on 96 patients admitted in the Department of Surgery, Rohilkhand Medical College & Hospital, Bareilly during the period of 1st January 2010 to 31st December 2012. Results: Among the total of 36 patients (37.5%) from urban area, 16 (16.6%) were males and 20 (20.8%) were females and from rural area 46 (47.9%) were male and 14 (14.6) were female. The most frequent etiological agent was hot liquid (45.8%) followed by flame burns (33.3%), chemical (13.5%) and electrical (7.2%). Out of the total patients, 47 (48.9%) had 1 and 2 degree burn, 32 (33.3%) had 3 degree burn and 17 (17.7%) had mixed burn. Out of the total of 20 patients, who had died 6 were males and 14 were females. Conclusion: The most frequent cause of burn in Rohilkhand region was hot liquid. The mortality rate was higher for females than males.

Gabapentin for refractory idiopathic trigeminal neuralgia.

Trigeminal neuralgia is sudden, usually unilateral, severe, stabbing, brief recurrent pain in the distribution area of one or more of the branches of trigeminal nerve. Various pharmacological agents including carbamazepine, oxcarbazepine, phenytoin, lamotrigine, baclofen and clonazepam have been tried with variable success rate. Here a case of idiopathic trigeminal neuralgia is presented. The patient presented in the emergency room with severe pain in the distribution area of maxillary branch of trigeminal nerve, resistant to conventional pharmacotherapy, managed successfully with gabapentin without untoward side-effects.

Self-extubation in intensive care and re-intubation predictors: a retrospective study.

To find out the incidence of self-extubation in intensive care, to evaluate the factors responsible for it and to identify the predictors of need for re-intubation, a retrospective analysis was conducted among 350 patients who were admitted to the intensive care unit over a two-year period and required ventilatory therapy for more than 48 hours. In all patients who self-extubated, the demographic data, ventilatory parameters before self-extubation (mode of ventilation, inspired oxygen concentration, positive end-expiratory pressure), partial pressure of oxygen in arterial blood and inspired oxygen fraction ration (PaO2/FiO2), and the event of re-intubation were noted. These values were compared among patients who were re-intubated and those who were not. Twelve patients out of 350 self-extubated. Of these 12 patients, 7 required re-intubation while 5 did not. Of these 7 patients, 3 died within 48 hours of the episode of self-extubation and one patient's death was directly attributable to self-extubation. Of the remaining 4 patients, 3 died within a span of 7 days. Re-intubation after self-extubation should not be considered mandatory. Patients who required re-intubation had lower PaO2/FiO2 than patients who did not.