Estimating disease prevalence from two-phase surveys with non-response at the second phase.
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In this paper we compare several methods for estimating population disease prevalence from data collected by two-phase sampling when there is non-response at the second phase. The traditional weighting type estimator requires the missing completely at random assumption and may yield biased estimates if the assumption does not hold. We review two approaches and propose one new approach to adjust for non-response assuming that the non-response depends on a set of covariates collected at the first phase: an adjusted weighting type estimator using estimated response probability from a response model; a modelling type estimator using predicted disease probability from a disease model; and a regression type estimator combining the adjusted weighting type estimator and the modelling type estimator. These estimators are illustrated using data from an Alzheimer's disease study in two populations. (+info)
Folate and vitamin B12 status of adolescent girls in northern Nigeria.
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The diets of populations in many developing countries are low in folate and vitamin B12 and a deficiency of either of these vitamins results in increased risk for cardiovascular disease and neural tube defects. The rates of neural tube defects in Nigeria are among the highest reported worldwide. Since many girls marry at an early age in northern Nigeria, we therefore determined the folate and vitamin B12 status of adolescent girls between 12 and 16 years of age in Maiduguri, Nigeria. The mean serum folate concentration for subjects was 15.3 +/- 5.2 nmol/L. Whereas only four subjects (2.4%) had serum folate concentrations lower than 6.8 nmol/L, a level indicative of negative folate balance, 9% of the subjects had serum vitamin B12 concentrations at or below 134 pmol/L, the lower limit of the reference range for their age group. Serum homocysteine was measured in 56 of the 162 subjects and the mean level was 15.9 +/- 5.0 mumol/L. The majority of subjects had serum homocysteine concentrations above the upper limit of the reference range for their age group. We conclude that the adolescent girls we studied were at greater risk for vitamin B12 deficiency than folate deficiency. This conclusion is consistent with the fact that their diet included few foods that contained vitamin B12. (+info)
Job satisfaction of doctors in Negeri Sembilan.
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A cross sectional study was carried out in Negeri Sembilan to identify factors associated with job satisfaction of doctors serving in Ministry of Health and their intentions to resign. All Ministry of Health doctors currently working in Negeri Sembilan were included in the study and data collection was done via a self-administered postal questionnaire. The response rate was 69.4%. Out of those who responded, only 31.3% had global job satisfaction, with the majority dissatisfied. Intention to resign was high among 32.7% of the respondents. Factors found to be significantly associated with job satisfaction were age, job designation, income, duration of service and intention to resign. Intention to resign was found to be significantly associated with ethnicity and income. From logistic regression, predictors of job satisfaction identified were age, place of first graduation, and satisfaction with status and autonomy, satisfaction with career development, satisfaction with workload and satisfaction with transfers. Predictors of intention to resign were race, income and global job satisfaction. (+info)
Serum ferritin and other haematological measurements in apparently healthy adults with malaria parasitaemia in Lagos, Nigeria.
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We studied 300 apparently healthy residents of Lagos aged 16-57 years. Their mean ferritin levels were 99.6 +/- 50.5 microg/l (men aged 20-57) and 66.5 +/- 44 microg/l (women aged 20-53) in aparasitaemic individuals. In parasitaemic subjects, mean ferritin levels were 133.1 +/- 48.3 microg/l (men aged 20-56) and 114.8 +/- 51.1 microg/l (women aged 16-50). Mean haematocrit values for aparasitaemic males were 45.7 +/- 5.6% and 37.9 +/- 5% for females, while mean haemoglobin levels were 153.2 +/- 1.5 microg/l and 124 +/- 3 microg/l, respectively. The mean values for MCV (mean corpuscular volume), MCH (mean corpuscular haemoglobin), MCHC (mean corpuscular haemoglobin concentration) were 101.7 +/- 8fl, 30.6 +/- 2.2 pg, 335 +/- 0.4 g/l and 99.8 +/- 10.1fl, 29.1 +/- 6.5 pg, 335 +/- 6 g/l. Serum iron levels were 34.2 +/- 5 micromol/l and 29.5 +/- 77 micromol/l. All haematological parameters measured were similar in both malaria parasitaemia positive and negative subjects, except ferritin level which was significantly higher in parasitaemic individuals (P < 0.05). Ferritin concentration and malaria density (r = 0.76 in males, r = 0.74 in females, P < 0.05) were positively correlated. Ferritin levels of subjects infected with Plasmodium falciparum were significantly higher than of those infected with P. malariae (P < 0.05). Hence ferritin estimation without examination for malaria parasitaemia in a malaria-endemic region such as Nigeria is not reliable. Asymptomatic malaria parasitaemia increases the ferritin level. Considering the mean ferritin level we found in normal subjects on a balanced diet, routine iron supplementation may not be necessary in the treatment of malaria-induced anaemia in Nigeria. (+info)
Body size at birth and blood pressure among children in developing countries.
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BACKGROUND: Studies in developed countries have shown that reduced fetal growth is related to raised blood pressure in childhood and adult life. Little is known about this association in developing countries, where fetal growth retardation is common. METHODS: In 1994-1995, we measured blood pressure in 1570 3-6-year-old children living in China, Guatemala, Chile, Nigeria and Sweden. We related their blood pressure to patterns of fetal growth, as measured by body proportions at birth. The children were all born after 37 weeks gestation and weighed more than 2.5 kg at birth. RESULTS: In each country, blood pressure was positively related to the child's current weight. After adjusting for this and gender, systolic pressure was inversely related to size at birth in all countries except Nigeria. In Chile, China and Guatemala, children who were proportionately small at birth had raised systolic pressure. For example, in Chile, systolic pressure adjusted for current weight increased by 4.9 mmHg (95% CI : 2.1, 7.7) for every kilogram decrease in birthweight, by 1 mmHg (95% CI : 0.4, 1.6) for every centimetre decrease in birth length, and by 1.3 mmHg (95% CI : 0.4, 2.2) for every centimetre decrease in head circumference at birth. In Sweden, systolic pressure was higher in children who were disproportionately small, that is thin, at birth. Systolic pressure increased by 0.3 mmHg (95% CI : 0.0, 0.6) for every unit (kg/m3) decrease in ponderal index at birth. These associations were independent of the duration of gestation. CONCLUSIONS: Raised blood pressure among children in three samples from China, Central and South America is related to proportionate reduction in body size at birth, which results from reduced growth throughout gestation. The relation between fetal growth and blood pressure may be different in African populations. Proportionately reduced fetal growth is the prevalent pattern of fetal growth retardation in developing countries, and is associated with chronic undernutrition among women. Improvement in the nutrition and health of girls and young women may be important in preventing cardiovascular disease in developing countries. (+info)
Pattern of drug use amongst antenatal patients in Benin City, Nigeria.
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BACKGROUND: Drugs taken by pregnant women could have profound effect on pregnancy outcome for both the mother and fetus. In most developing country regulation of drug is poor, access is unrestricted and abuse of drugs especially antibiotics is rampant. The study was undertaken to determine the pattern and extent of drug consumption amongst pregnant women in Benin City. METHODS: A cross-sectional study of 1200 pregnant patients at various gestational ages was undertaken, using a structured questionnaire to obtain details of the extent and character of drug use before or during pregnancy. FINDINGS: Folic acid was taken by 76.08% of all the pregnant patients, while anti-malarial drugs were taken by 19.75%; 15.83% used the drugs on doctors' prescription and 3.92% without a doctor's prescription. The proportion of the mothers that consumed native herbs was 12.08%. The use of native medication was more prevalent amongst nulliparous mothers (41.82%). Native herb consumption decreased with increase in parity. Both educated and illiterate mothers consumed herbal medications. Less than 1% of the mothers smoke cigarettes. INTERPRETATION: In Benin City drug use in pregnancy is characterized by a pattern of low consumption except folic acid and native herbs. This could be a major setback for any program of drug intervention, as in chemoprophylaxis for malaria in pregnancy. Much resource will be needed for patients' education for successful implementation of any planned program in the community. (+info)
Fungal air spora at Ibadan, Nigeria.
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The fungal air spora at Ibadan, Nigeria, was investigated by using Casella Slit Samplers. Three sites, incorporating three locations at each site, were selected for the exposure of replicate plates during sampling. To provide data on a wide range of saprophytic and pathogenic fungal spores, isolations were made on Sabouraud dextrose agar and malt agar plates incubated at 26 and 37 C. Altogether over 60,000 fungal colonies were isolated and counted during the 12-month sampling period. The prevalent fungal genera recorded were: Cladosporium, Curvularia, Fusarium, Aspergillus, Penicillium, Pithomyces, Aureobasidium, Geotrichum, Phoma, Nigrospora, Epicoccum, and Neurospora. The wet and dry seasons (indicated by the temperature, relative humidity, and rainfall data) caused seasonal periodicity in colony numbers. The influence of culture media on the isolated colonies was not significant when the total number of isolated colonies were considered on a monthly basis, but in reviewing a few of the fungal genera there were marked differences between the two media, especially with Pithomyces. Attempts were made to identify some of the isolated colonies by species, e.g., Aspergillus carneus, Aspergillus flavus, Aspergillus fumigatus, Curvularia geniculata, Fusarium oxysporum, Penicillium herquei, Pithomyces chartaum, Rhizopus arrhizus, and Syncephalastrum racemosum. Such identifications proved a basis for further studies on the role of these fungal species in the frontier problem of contamination and biodegradation of drugs and pharmaceuticals, allergies and other problems in the local environment. (+info)
Evidence for a reduced effect of chloroquine against Plasmodium falciparum in alpha-thalassaemic children.
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Alpha-thalassaemia is common in malaria-endemic regions and is considered to confer protection from clinical disease due to infection with Plasmodium falciparum. In vitro, sensitivity to chloroquine (CQ) of P. falciparum infecting alpha-thalassaemic erythrocytes is reduced. We examined, in a cross-sectional study of 405 Nigerian children, associations between alpha-globin genotypes, blood concentrations of CQ, and P. falciparum parasitaemia. Of the children, 44% were alpha+-thalassaemic (36.8% heterozygous, 7.6% homozygous). CQ in blood and P. falciparum-infection were observed in 52 and 80%, respectively. CQ was more frequently found in homozygous alpha+-thalassaemic (71%) than in non-thalassaemic children (50%; odds ratio, 2.42; 95% confidence interval, 1.01-5.8). Among children with CQ in blood and despite similar drug concentrations, alpha+-thalassaemic individuals had fewer infections below the threshold of microscopy which were detectable by PCR only, and they had a higher prevalence of elevated parasitaemia than non-thalassaemic children. No such differences were discernible among drug-free children. CQ displays a lowered efficacy in the suppression of P. falciparum parasitaemia in alpha+-thalassaemic children; hence protection against malaria due to alpha+-thalassaemia may be obscured in areas of intense CQ usage. Moreover, alpha+-thalassaemia may contribute to the expansion of CQ resistance. (+info)