Classification rates: non‐parametric verses parametric models using binary data

Estimations of the conditional mean and the marginal effects for particular small changes in the covariates have been of interest in financial, economics and even educational sectors. The standard approach has been to specify a parametric model such as probit or logit and then estimating the coefficients by maximum likelihood method. This is only applicable when the distribution form from which the data has been drawn is known. Non parametric methods have been proposed when the functional form assumptions cannot be ascertained. This research sought to establish if non parametric modeling achieves a higher correct classification ratio than a parametric model. The local likelihood technique was used to model fit the data sets. The same sets of data were modeled using parametric logit and the abilities of the two models to correctly predict the binary outcome compared. The results obtained showed that non‐parametric estimation gives a better prediction rate (classification ratio) for a binary data than parametric estimation. This was achieved both empirically and through simulation. For empirical results two different data sets were used. The first set consisted of loan applications of customers and the second set consisted of approved loans. In both data sets the classification ratio for non‐parametric method was found to be 1 while that for parametric was found to be 0.87 (only 87 out of the 100 observations were correctly classified) and 0.83 respectively. Simulation was done based on sample sizes of 25, 50, 75, 100,150,200,250,300 and 500. The simulated results further showed that the accuracy of both models decrease as sample size increases.Key words: Parametric, non‐parametric, local likelihood, logit, confusion matrix and classification rati

Clinical Risk Index for Babies (Crib) Ii Score as a Predictor of Neonatal Mortality among Low Birth Weight Babies at Kenyatta National Hospital

Background: Neonatal deaths, especially among the Low Birth Weight (LBW) babies, are of major concern in the Newborn Unit (NBU) of Kenyatta National Hospital (KNH). Several instruments have been developed to predict initial mortality risk among the LBW babies. Among them is the scoring system Clinical Risk Index for Babies also known as CRIB II score.Objective: To evaluate the use of CRIB II score as a tool to predict the risk for neonatal mortality among the LBW babies at KNH.Design: A prospective cohort study.Setting: Newborn Unit of Kenyatta National Hospital.Subject: A total sample of 135 low birth weight babies were followed up from admission till discharge, the 28th day of life or death whichever came first.Results: One hundred and thirty five newborns were enrolled into the study. Birth weight ranged from 600 – 2500g, with a median of 1600g. Total CRIB II score ranged from 1 – 15, with a median of 5.5. Gestational age ranged from 26 – 38 weeks. Total mortality was 45.9%. Birth weight <1500g, gestational age <30 weeks, base excess <-12mmol/l, temperature at admission >37.5 or <35 (all components of CRIB II) and total CRIB II score of > 4 were all found to be significantly associated with hospital neonatal mortality. Using a cut off point of 4, CRIB II score was found to have a sensitivity of 80.6%, specificity of 75.3%, and a predictive value of 77.7% compared to 72.5, 71.2, and 71.8% respectively for birthweight. Gestational age was found to have even lower figures; 56, 75 and 66% for sensitivity, specificity and predictive values respectively.Conclusion: CRIB II score of > 4 was found to have better prediction for mortality among the LBW babies at KNH-NBU compared to the traditionally used predictors and can be used to prioritise care for such neonates for better outcome

Clinical features, predictive factors and outcome of hyperglycaemic emergencies in a developing country

<p>Abstract</p> <p>Background</p> <p>Hyperglycaemic emergencies are common acute complications of diabetes mellitus (DM) but unfortunately, there is a dearth of published data on this entity from Nigeria. This study attempts to describe the clinical and laboratory scenario associated with this complication of DM.</p> <p>Methods</p> <p>This study was carried out in DM patients who presented to an urban hospital in Nigeria with hyperglycaemic emergencies (HEs). The information extracted included biodata, laboratory data and hospitalization outcome. Outcome measures included mortality rates, case fatality rates and predictive factors for HEs mortality. Statistical tests used are <it>χ</it>², Student's t test and logistic regression.</p> <p>Results</p> <p>A total of 111 subjects with HEs were recruited for the study. Diabetes ketoacidosis (DKA) and hyperosomolar hyperglycaemic state (HHS) accounted for 94 (85%) and 17 (15%) respectively of the HEs. The mean age (SD) of the subjects was 53.9 (14.4) years and their ages ranged from 22 to 86 years. DKA occurred in all subjects with type 1 DM and 73 (81%) of subjects with type 2 DM. The presence of HSS was noted in 17 (19%) of the subjects with type 2 DM.</p> <p>Hypokalaemia (HK) was documented in 41 (37%) of the study subjects. Elevated urea levels and hyponatraemia were noted more in subjects with DKA than in those subjects with HHS (57.5%,19% vs 53%,18%). The mortality rate for HEs in this report is 20% and the case fatality rates for DKA and HHS are 18% and 35% respectively.</p> <p>The predictive factors for HEs mortality include, sepsis, foot ulceration, previously undetected DM, hypokalaemia and being elderly.</p> <p>Conclusion</p> <p>HHS carry a higher case fatality rate than DKA and the predictive factors for hyperglycaemic emergencies' mortality in the Nigerian with DM include foot ulcers, hypokalaemia and being elderly.</p

Porn video shows, local brew, and transactional sex: HIV risk among youth in Kisumu, Kenya

Background: Kisumu has shown a rising HIV prevalence over the past sentinel surveillance surveys, and most new infections are occurring among youth. We conducted a qualitative study to explore risk situations that can explain the high HIV prevalence among youth in Kisumu town, Kenya Methods: We conducted in-depth interviews with 150 adolescents aged 15 to 20, held 4 focus group discussions, and made 48 observations at places where youth spend their free time. Results: Porn video shows and local brew dens were identified as popular events where unprotected multipartner, concurrent, coerced and transactional sex occurs between adolescents. Video halls - rooms with a TV and VCR - often show pornography at night for a very small fee, and minors are allowed. Forced sex, gang rape and multiple concurrent relationships characterised the sexual encounters of youth, frequently facilitated by the abuse of alcohol, which is available for minors at low cost in local brew dens. For many sexually active girls, their vulnerability to STI/HIV infection is enhanced due to financial inequality, gender-related power difference and cultural norms. The desire for love and sexual pleasure also contributed to their multiple concurrent partnerships. A substantial number of girls and young women engaged in transactional sex, often with much older working partners. These partners had a stronger socio-economic position than young women, enabling them to use money/gifts as leverage for sex. Condom use was irregular during all types of sexual encounters. Conclusions: In Kisumu, local brew dens and porn video halls facilitate risky sexual encounters between youth. These places should be regulated and monitored by the government. Our study strongly points to female vulnerabilities and the role of men in perpetuating the local epidemic. Young men should be targeted in prevention activities, to change their attitudes related to power and control in relationships. Girls should be empowered how to negotiate safe sex, and their poverty should be addressed through income-generating activities.</p

The impact of HIV-1 on the malaria parasite biomass in adults in sub-Saharan Africa contributes to the emergence of antimalarial drug resistance

Background. HIV-related immune-suppression increases the risk of malaria (infection, disease and treatment failure) and probably the circulating parasite biomass, favoring the emergence of drug resistance parasites. Methods. The additional malaria parasite biomass related to HIV-1 co-infection in sub-Saharan Africa was estimated by a mathematical model. Parasite biomass was computed as the incidence rate of clinical malaria episodes multiplied by the number of parasites circulating in the peripheral blood of patients at the time symptoms appear. A mathematical model estimated the influence of HIV-1 infection on parasite density in clinical malaria by country and by age group, malaria transmission intensity and urban/rural area. In a multivariate sensitivity analysis, 95% confidence intervals (CIs) were calculated using the Monte Carlo simulation. Results. The model shows that in 2005 HIV-1 increased the overall malaria parasite biomass by 18.0% (95%CI: 11.6-26.9). The largest relative increase (134.9-243.9%) was found in southern Africa where HIV-1 prevalence is the highest and malaria transmission unstable. The largest absolute increase was found in Zambia, Malawi, the Central African Republic and Mozambique, where both malaria and HIV are highly endemic. A univariate sensitivity analysis shows that estimates are sensitive to the magnitude of the impact of HIV-1 infection on the malaria incidence rates and associated parasite densities. Conclusion. The HIV-1 epidemic by increasing the malaria parasite biomass in sub-Saharan Africa may also increase the emergence of antimalarial drug resistance, potentially affecting the health of the whole population in countries endemic for both HIV-1 and malaria

Association Analysis of the FTO Gene with Obesity in Children of Caucasian and African Ancestry Reveals a Common Tagging SNP

Recently an association was demonstrated between the single nucleotide polymorphism (SNP), rs9939609, within the FTO locus and obesity as a consequence of a genome wide association (GWA) study of type 2 diabetes in adults. We examined the effects of two perfect surrogates for this SNP plus 11 other SNPs at this locus with respect to our childhood obesity cohort, consisting of both Caucasians and African Americans (AA). Utilizing data from our ongoing GWA study in our cohort of 418 Caucasian obese children (BMI≥95th percentile), 2,270 Caucasian controls (BMI<95th percentile), 578 AA obese children and 1,424 AA controls, we investigated the association of the previously reported variation at the FTO locus with the childhood form of this disease in both ethnicities. The minor allele frequencies (MAF) of rs8050136 and rs3751812 (perfect surrogates for rs9939609 i.e. both r2 = 1) in the Caucasian cases were 0.448 and 0.443 respectively while they were 0.391 and 0.386 in Caucasian controls respectively, yielding for both an odds ratio (OR) of 1.27 (95% CI 1.08–1.47; P = 0.0022). Furthermore, the MAFs of rs8050136 and rs3751812 in the AA cases were 0.449 and 0.115 respectively while they were 0.436 and 0.090 in AA controls respectively, yielding an OR of 1.05 (95% CI 0.91–1.21; P = 0.49) and of 1.31 (95% CI 1.050–1.643; P = 0.017) respectively. Investigating all 13 SNPs present on the Illumina HumanHap550 BeadChip in this region of linkage disequilibrium, rs3751812 was the only SNP conferring significant risk in AA. We have therefore replicated and refined the association in an AA cohort and distilled a tag-SNP, rs3751812, which captures the ancestral origin of the actual mutation. As such, variants in the FTO gene confer a similar magnitude of risk of obesity to children as to their adult counterparts and appear to have a global impact

Diabetic ketoacidosis

Diabetic ketoacidosis (DKA) is the most common acute hyperglycaemic emergency in people with diabetes mellitus. A diagnosis of DKA is confirmed when all of the three criteria are present — ‘D’, either elevated blood glucose levels or a family history of diabetes mellitus; ‘K’, the presence of high urinary or blood ketoacids; and ‘A’, a high anion gap metabolic acidosis. Early diagnosis and management are paramount to improve patient outcomes. The mainstays of treatment include restoration of circulating volume, insulin therapy, electrolyte replacement and treatment of any underlying precipitating event. Without optimal treatment, DKA remains a condition with appreciable, although largely preventable, morbidity and mortality. In this Primer, we discuss the epidemiology, pathogenesis, risk factors and diagnosis of DKA and provide practical recommendations for the management of DKA in adults and children

Drug abuse in Kisumu town western Kenya

This was a cross sectional study designed to determine the factors associated with drug abuse among secondary school students in nine schools in Kisumu town, western Kenya. The objective of this study was to determine the effect of age, gender and peer influence on drug abuse and to establish the reasons why students abuse drugs. Nine schools were randomly selected for the study. A total of 458 students (243 males and215 females) were interviewed using a closed ended questionnaire. The data were then categorized into non-abusers and abusers and the degree of association between the variables was tested using Chi-square test. A total of 458 students (243 males and 215 females), were interviewed using a close-ended questionnaire. The results showed that 265 (57.9%) of the respondents had consumed alcohol at least once in their lives,159 (34.7%) had abused tobacco, 84 (18.3%) had abused cannabis, 106 (23.1%) had abused khat and 24 (5.2%) had used inhalants and/or cocaine. The age group most at risk was 16-18 years, the age at which most students are in secondary school. The reasons given for the abuse of the drugs were: experimentation 92 (38.2%), enjoyment of the feeling they experience 114 (47.3%), influence from friends 21 (8.7%),influence from relatives 5 (2.1%) and for treating stomach ailments 7 (2.9%). More boys were found to be abusing drugs (36.9%, n = 169) compared to girls (27.3%, p = 0.007). Also, drug abuse was found to be higher in students living in low socioeconomic class areas of the town (30%, n = 122) compared to high-class areas (21.6%, n = 94, p =0.004) and peer influence had no effect on drug abuse (p = 0.249). From this study it was concluded that drug abuse was widespread in secondaryschools in Kisumu and although it affected both sexes boys were more involved in the practice than girls. The study therefore recommends that early intervention should target school attendees at early age with the aim of preventing drug abuse in secondary schools in Kisumu town, western Kenya

Growth and development of abandoned babies in institutional care in Nairobi

Objective: To determine the pattern of growth and development of institutionalised infants and to compare the outcome with that of infants living with their biological 1 mothers.Design: A cross-sectional survey.Setting: Seven children's homes; Kenyatta National Hospital's New Born Unit and Well Baby Clinics in Nairobi, KenyaParticipants: Eighty two abandoned babies who fullfilled the selection criteria were recruited and for each abandoned baby two mothered babies matched for age and sex were selected from the well baby clinicsMain outcome measures: Anthropometric measures of weight, length, head circumference and left mid arm circumference (LUMAC) were taken and the mean values and Z scores determined to demonstrate growth pattern and nutritional status of the babies. The Revised Denver Development Screening Test (RDDST) was used to assess the development pattern of infantsResults: Seventy per cent of infants were below six months old and 73% were abandoned within the first week of life. Abandoned babies were significantly thinner with the mean LUMAC of 10.8 em versus 123 cm (p=0.02) Institutionalised babies were significantly wasted (p=0.00001) and stunted (p=0.00001). Abandoned babies were significantly delayed in development (p4.0001). In all the four sectors tested tor, institutionalised babies showed signirlcant delay, p&lt;0.0001 in each sector.Conclusion: This study demonstrates that infants under institutional care have poorer growth and development compared to mothered infants

Career Intentions of Medical Students Trained in Six Sub-Saharan African Countries

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