published_or_final_version / Journalism and Media Studies Centre / Doctoral / Doctor of Philosophy

Cardiovascular disease (CVD) is a major health problem among women worldwide. In Thailand, risk factors of CVD in rural Thai women have not yet been examined. The purpose of this predictive correlational study was to examine risk factors of CVD in rural Thai women. Non-modifiable risk factors, modifiable risk factors (physiological, behavioral, and psychological risk factors), contextual risk factors, as well as, coping were conceptualized as major variables in this study.The sample consisted of 149 rural Thai women who had been diagnosed with CVD and resided in rural northern Thailand. A set of questionnaires and physiological measures were used to obtain data. The Chi-square test and the Pearson correlation technique, as well as the Multiple regression were used for data analysis.The results revealed that age, hypertension, cigarette smoking, stress, depression, and poverty had positive relationships with the severity of CVD. BMI, physical activity, education level, and family income were inversely related to the severity of CVD. However, total cholesterol, diabetes mellitus, menopause status, alcohol consumption, distance to hospital, transportation to health care, and coping had no relationship to the severity of CVD. A few of the physiological and behavioral risk factors were significant predictors of the severity of CVD in rural Thai women. These included high blood pressure, cigarette smoking, and physical inactivity. Notably, psychological stress and the contextual risk factors of income and poverty were also significant predictors of the severity of CVD in these women. Moreover, there were the significant moderator effects in predicting to the severity of CVD: total serum cholesterol and family income, diabetes and distance to a hospital, BMI and transportation, menopause and income, cigarette smoking and transportation, and depression and poverty.In conclusion, the findings from this study suggested that few of traditional risk factors of CVD were significant risk factors for CVD. Noteworthy findings demonstrated that psychological stress and contextual risk factors played an important role in contributing to CVD in rural Thai women. It is suggested that specific and effective interventions are needed for these women in order to reduce their morbidity and mortality rates of CVD.

Introduction Coronary artery disease (CAD) is the most common cause of death in Europe and North America and early detection of atherosclerosis is a clinical priority. Diagnosis of CAD remains conventional angiography, although recent technology has introduced non-invasive imaging of coronary arteries using computed tomographic coronary angiography (CTCA), which enables the detection and quantification of coronary artery calcification (CAC). CAC forms within the arterial wall and is usually found in or adjacent to atherosclerotic plaques and is consequently known as sub-clinical atherosclerosis.  The conventional cardiovascular (CV) risk factors used to quantify the estimated 10-year coronary event risk comprise dyslipidaemia, hypertension, diabetes mellitus, obesity, smoking and family history of CAD. Nevertheless, their relationship with significant (>50%) stenosis, their interaction with the CAC score and their predictive ability for CAC presence and extent has not been fully determined in symptomatic patients.   Methods   For Papers 1-4 we took patients from the Euro-CCAD cohort, an international study established in 2009 in Umeå, Sweden. The study data gave us the CAC score and the CV risk factor profile in 6309 patients, together with angiography results for a reduced cohort of 5515 patients. In Papers 1 and 2 we assessed the risk factors for significant stenosis, including CAC as a risk factor. Paper 2 carried out this analysis by geographical region: Europe vs USA and northern vs southern Europe. Paper 3 investigated the CV risk factors for CAC presence, stratified by age and gender, while Paper 4 assessed the CV risk factors for CAC extent, stratified by gender.  In paper 5 we carried out a systematic review and meta-analysis of all studies of the risk factor predictors of CAC presence, extent and progression in symptomatic patients. From a total of 884 studies, we identified 10 which fitted our inclusion criteria, providing us with a total of 15,769 symptomatic patients. All 10 were entered in the systematic review and 7 were also eligible for the meta-analysis.   Results Paper 1:           Among risk factors alone, the most powerful predictors of significant coronary stenosis were male gender followed by diabetes, smoking, hypercholesterolaemia, hypertension, family history of CAD and age; only obesity was not predictive. When including the log transformed CAC score as a risk factor, this proved the most powerful predictor of >50% stenosis, but hypercholesterolaemia and hypertension lost their predictive ability. The conventional risk factors alone were 70% accurate in predicting significant stenosis, the log transformed CAC score alone was 82% accurate but the combination was 84% accurate and improved both sensitivity and specificity.  Paper 2:           Despite some striking differences in profiles between Europe and the USA, the most important risk factors for >50% stenosis in both groups were male gender followed by diabetes. When the log CAC score was included as a risk factor, it became by far the most important predictor of >50% stenosis in both continents, followed by male gender. In the northern vs southern Europe comparison the result was similar, with the log CAC score being the most important predictor of >50% stenosis in both regions, followed by male gender.  Paper 3:           Independent predictors of CAC presence in males and females were age, dyslipidaemia, hypertension, diabetes and smoking, with the addition of family history of CAD in males; obesity was not predictive in either gender. The most important predictors of CAC presence in males were dyslipidaemia and diabetes, while among females the most important predictors of CAC presence were diabetes followed by smoking. When analysed by age groups, in both males and females aged <70 years, diabetes, hypertension and dyslipidaemia were predictive, with diabetes being the strongest; in females aged <70 years, smoking was also predictive. Among those aged ≥70 years, the results are completely different, with only dyslipidaemia being predictive in males but smoking and diabetes were predictive in females.  Paper 4:           In the total cohort, age, male gender, diabetes, obesity, family history of CAD and number of risk factors predicted an increasing CAC score, with the most important being male gender and diabetes. In males, hypertension and dyslipidaemia were also predictive, although diabetes was the most important predictor. Diabetes was similarly the most important risk factor in females, followed by age and number of risk factors. Among patients with CAC, hypertension, dyslipidaemia and diabetes predicted CAC extent in both males and females, with diabetes being the strongest predictor in males followed by dyslipidaemia, while diabetes was also the strongest predictor in females, followed by hypertension. Quantile regression confirmed the consistent predictive ability of diabetes.  Paper 5:           In the systematic review, age was strongly predictive of both CAC presence and extent but not of CAC progression. The results for CAC presence were overwhelmed by data from one study of almost 10,000 patients, which found that white ethnicity, diabetes, hypertension and obesity were predictive of CAC presence but not male gender, dyslipidaemia, family history or smoking. With respect to CAC extent, only male gender and hypertension were clearly predictive, while in the one study of CAC progression, only diabetes and hypertension were predictive. In the meta-analysis, hypertension followed by male gender, diabetes and age were predictive of CAC presence, while for CAC extent mild-moderate CAC was predicted by hypertension alone, whereas severe CAC was predicted by hypertension followed by diabetes.   Conclusion Our investigation of the Euro-CCAD cohort showed that the CAC score is far more predictive of significant stenosis than risk factors alone, followed by male gender and diabetes, and there was little benefit to risk factor assessment over and above the CAC score for >50% stenosis prediction. Regional variations made little difference to this result. Independent predictors of CAC presence were dyslipidaemia and diabetes in males and diabetes followed by smoking in females. The risk factor predictors alter at age 70. The most important risk factor predictors of CAC extent were male gender and diabetes; when analysed by gender, diabetes was the most important in both males and females. Our studies have consistently shown the strong predictive ability of male gender in the total cohort and diabetes in males and females and this is reflected in the meta-analysis, which also found hypertension to be independently predictive. Interestingly, dyslipidaemia does not appear to be a strong risk factor.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / OBJECTIVE: An estimated 20-30% of patients with primary Clostridium difficile infection (CDI) develop recurrent CDI (rCDI) within 2 weeks of completion of therapy. While the actual mechanism of recurrence remains unknown, a variety of risk factors have been suggested and studied. The aim of this systematic review and meta-analysis was to evaluate current evidence on the risk factors for rCDI. DESIGN: We searched MEDLINE and 5 other databases for subject headings and text related to rCDI. All studies investigating risk factors of rCDI in a multivariate model were eligible. Information on study design, patient population, and assessed risk factors were collected. Data were combined using a random-effects model and pooled relative risk ratios (RRs) were calculated. RESULTS: A total of 33 studies (n=18,530) met the inclusion criteria. The most frequent independent risk factors associated with rCDI were age≥65 years (risk ratio [RR], 1.63; 95% confidence interval [CI], 1.24-2.14; P=.0005), additional antibiotics during follow-up (RR, 1.76; 95% CI, 1.52-2.05; P<.00001), use of proton-pump inhibitors (PPIs) (RR, 1.58; 95% CI, 1.13-2.21; P=.008), and renal insufficiency (RR, 1.59; 95% CI, 1.14-2.23; P=.007). The risk was also greater in patients previously on fluoroquinolones (RR, 1.42; 95% CI, 1.28-1.57; P<.00001). CONCLUSIONS: Multiple risk factors are associated with the development of rCDI. Identification of modifiable risk factors and judicious use of antibiotics and PPI can play an important role in the prevention of rCDI.

ABSTRACT Teenage pregnancy is a health and social problem in Malawi as a result of physical, psychological and socio-economic consequences on the teenage mother, family and the society as a whole. Although studies have been conducted on the prevalence and risk factors that cause teenage pregnancy in Malawi before, detailed reports are scanty, especially for Zomba district. In spite of studies and interventions that have been and are being implemented, the prevalence of unplanned teenage pregnancy in Malawi is still high, suggesting that more efforts are required to achieve effective preventive measures. The aim of this study was to explore risk factors such as cultural issues, non-use of contraceptives, lack of knowledge on sexual and reproductive health, circumstances of first sex, gender power dynamics, sexual and physical violence, age difference between teenage girls and their partners and socio-economic status for unplanned teenage pregnancy in Zomba district of Malawi. A cross-sectional analytic design was used. Five antenatal clinics were selected using a stratified and simple random sampling technique. Data were obtained from 505 participants under the age of 20 years using a questionnaire administered through face-to-face interviews. Descriptive statistics were used to analyse data and comparisons between planned and unplanned teenage pregnancy were conducted using the Chi-squared (P ≤ 0.05) and logistic regression model to predict factors for unplanned pregnancy. Findings reveal that unplanned pregnancy accounted for 76.4% of teenagers attributable to early sex and marriage, low contraceptive use, educational levels and socio-economic status, lack of knowledge of reproductive and sexual health, physical and sexual violence and substance abuse, transactional sex due to poverty, early school dropout, misleading counselling causing a lack of knowledge on sexual and reproductive health and gender inequalities. Recommendations made are aimed at eliminating myths and misconceptions surrounding the use of contraceptives and condoms, empowering teenagers economically and in decision making, promoting career guidance, awareness on human rights, including sexual and reproductive rights and implications of early marriage and training of traditional counsellors. A multisectoral approach, including government, Non-Governmental Organisations (NGOs) and communities, is required to implement these recommendations.

MSc (Med), Epidemiology and Biostatistics, Faculty of Health Sciences, University of the Witwatersrand / Introduction: Tuberculosis (TB) persists as a serious global public heath problem of a magnitude requiring urgent attention. The increase in new cases of TB in African countries where the prevalence of HIV is relatively low has been associated with other host and environmental factors. There is little or no comparable data on the association between host and environmental related factors and TB incidence in low HIV prevalence regions of South Africa. Objectives: This study aims to investigate host and environmental factors associated with incident TB in one region of South Africa. Methods: 3493 TB-free participants were recruited, and baseline data collected at the beginning of 2003 in the Lung Health Study in Ravensmead and Uitsig, Cape Town, South Africa. The TB register was used to identify new cases among the 3493 participants between 2003 and 2007. Results: Of the 3493 study participants, 109 developed TB; i.e. 57 males and 52 females. The incidence of TB in the Ravensmead and Uitsig study population was 632 per 100 000. Cohabiting, OR= 2.09 (95% CI= 1.05 - 4.17), smoking, OR= 2.19 (95% CI= 1.48 - 4.14), and history of imprisonment OR= 1.88 (95% CI= 1.09 - 3.23) were all statistically associated with TB incidence in multiple logistic regression models. The summary population attributable fraction for these three factors was 53.2%. Conclusions: TB incidence was high in this community. Cigarette smoking was one of the most important predictors of TB incidence, and the proportion of smokers in this population was relatively high. TB control and prevention strategies need to focus on interventions which will reduce or limit the impact of TB risk factors.

MSc (Med), Population-Based Field Epidemiology, School of Public Health, Faculty of health Sciences, University of the Witwatersrand / Introduction: The achievements of the United Nations’ millennium development goals (MDGs) are not possible in isolation. Adult health and mortality with the exception of maternal health is one of the health issues that were openly missing among the list of MDGs. But eradicating extreme poverty and hunger would not be possible if the economically active population is not supported to be healthy and to live longer. Little has been done on adult health, especially to reduce mortality as compared to child health. Adult mortality is expected to equal or exceed child mortality in sub-Saharan Africa if nothing is done. There are varying factors associated with specific-causes of adult deaths within and among different settings. Obtaining more and better data on adult deaths and understanding issues relating to adult deaths in Africa are crucial for long life and development. Objectives: The study seeks to (i) describe causes of adult mortality, (ii) estimate adult cause-specific mortality rates and trends and (iii) identify risk factors of cause-specific mortality in the Ifakara Health and Demographic Surveillance System (IHDSS) population from 2003 – 2007 among adults aged 15 – 59 years. Methodology: The data for the study was extracted from the database of the Ifakara Health and Demographic Surveillance System (IHDSS) in Tanzania from 2003-2007. It was an open cohort study. The cohort was selected based on age (15-59years) and active residency from 1st January 2003 to 31st December 2007. Survival estimates were computed using Kaplan-Meier survival technique and adult mortality rates were estimated expressed per 1000 person years observed (PYO). Verbal autopsy method was used to ascertain causes of deaths. Cox proportional hazards method was used to identify socio-demographic factors associated with specific-causes of adult deaths. v Findings: A total 65,548 adults were identified and followed up, yielding a total of 184,000 person years. A total of 1,352 deaths occurred during the follow-up. The crude adult mortality rate (AMR) estimated over the period was 7.3/1000PYO. There was an insignificant steady increase in annual AMR over the period. The AMR in 2007 increased by 11% over year 2003. Most people died from HIV/AIDS (20.4%) followed by Malaria (13.2%). The AMR for the period was 2.49 per 1000PYO for communicable disease (CD) causes, 1.21 per 1000PYO for non communicable disease (NCD) causes and 0.53 per 1000PYO for causes related to accidents/injuries. Over the study period, deaths resulting from NCDs increased significantly by 50%. The proportion of deaths due to NCDs in 2003 was 16% increasing to 24% in year 2007. Adult deaths from Accidents/Injuries were significantly higher among men (hazard ratio (HR) = 2.2) after adjusting for socioeconomic status (SES), level of education and household size. For communicable and NCDs, most people died at home while for Accidents/Injuries most people died elsewhere (neither home nor health facility). The risk factors that were found to be associated with adult deaths due to NCDs were age and level of education. An improvement in level of education saw a reduction in the risk of dying from NCDs ((HR(Primary)=0.67, 95%CI:0.49, 0.92) and (HR(beyond Primary)=0.11, 95%CI:0.02, 0.40) after adjusting for age and sex. Age, SES and “entry type” were the factors found to be associated with dying from communicable diseases among the adults. In-migrants were 1.7 times more likely to die from communicable disease causes than residents having adjusted for age, household size, educational level, employment status of the head of household and SES. Conclusion: HIV/AIDS is the leading cause of adult deaths in IHDSS area followed by malaria. Most adult deaths occurred outside health facility in rural areas. This could probably be explained by the health seeking behavior and or health care accessibility in vi the rural area of sub-Saharan Africa. NCDs are increasing as a result of demographic and epidemiological transitions taking place in most African countries including Tanzania. Without preventions the rural community in Tanzania will soon face increased triple disease burden; (CD), NCD and Accident/Injuries. Policies on accident/injury preventions in developing countries will be effective if based on local evidence and research.

INTRODUCTION Cardiovascular diseases (CVD) are more common in kidney transplant recipients (KTRs) than in the general population. The high incidence of CVD in the KTRs can be attributed to traditional risk factors, additional risk factors associated with graft dysfunction and those specifically related to transplantation. Carotid intima-media thickness (cIMT) is a proven surrogate of atherosclerosis; it correlates with vessel pathology and is precisely imaged using ultrasound technology. This study was aimed at determining the prevalence and predictors of cardiovascular risk among KTRs at the Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) and to examine the relationship between cardiovascular risk factors and carotid intima media thickness. METHODS Patients aged 18 years and above who received a kidney transplant at the CMJAH between January 2005 and December 2009 were recruited. A questionnaire that captured cardiovascular risk factors was administered. Patients records were assessed for information on their post transplant follow up. All patients had echocardiography and carotid doppler done for measurement of intima-media thickness. The Framingham Risk Score was used to categorize patients into low, moderate, high risk and very high risk groups. Results were analyzed using statistical package for social sciences (SPSS) version 17, p value of 0.05 was considered significant. RESULTS One hundred (KTRs) 63 male (63%) and 37 female (37%) were recruited ranging in age from 19 to 70 years, with a mean age of 42.2 ± 12.42. Thirty six patients (36%) were found to have high cardiovascular risk. Multiple regression showed proteinuria (p = 0.022), higher cumulative steroid dosage (p = 0.028), elevated serum triglycerides (p = 0.04) and the presence of plaques in the carotid artery (p = 0.012) as predictors of higher cardiovascular risk.Carotid intima-media thickness correlates with higher CVD risk. Fourteen patients (14%) had a carotid artery plaque. Twenty five patients (25%) had cIMT of >0.7 mm. CONCLUSION Kidney transplant recipients in CMJAH were found to have high cardiovascular risk (36%) and carotid intima-media thickness correlates with this high CVD risk. Routine follow up of KTRs should include measurement of cIMT as it provides a simple non-invasive assessment of subclinical atherosclerosis.

ABSTRACT Odontogenic abscesses and Ludwig’s angina are infections commonly seen by maxillofacial surgeons. Both infections have periapical or periodontal origin and caused by oral bacteria. Ludwig’s angina is an aggressive and fast spreading infection compared to odontogenic abscess. The origin and the responsible bacteria of these infections are similar but the development and response is different in patients. There is no comprehensive study that has investigated the bacterial and host factors involved in the development of there infections. The aim of this study was to compare the presence of bacteria and enzymes in to the pus samples collected from patients with odontogenic abscess and Ludwig’s angina. Furthermore, various haematological and immunological tests were also compared between the two study groups. Forty two patients presenting with localized odontogenic abscesses and 15 with Ludwig’s angina were selected. Patient was examined according to standard protocol and history was recorded. Bloods were collected for haematology and immunology tests and pus was collected for microbiology and enzymatic tests. The results showed that highly virulent bacteria such as Staphylococcus aureus and black pigmented bacteroides were prevalent, increase in c-reactive protein, white blood cell count, IL6 and decrease in urea, circulating immune complexes and IgE in patients with Ludwig’s angina. Development of Ludwig’s angina could be due to the aggressive bacteria, their byproducts and low immune response compared to the odontogenic abscesses.

MSc (Med) Epidemiology and Biostatistics, Faculty of Health Sciences, University of the Witwatersrand, 2009 / Focus in public health research is shifting to the role of socio-economic factors in the promotion of health. Hence, an understanding of the roles socio-economic factors plays in improving health and health-seeking behaviour is important for public health policy. This study examined the relationship between socio-economic factors and HIV infection in rural Limpopo Province South Africa, an area characterized by poverty differentials and migration. Various possible social and economic risk factors (such as nationality, education status, marital status, employment status, migration status and socio-economic status) for HIV infection are analysed and discussed. This is secondary data analysis was carried out during the period June 2001 to March 2005 among 2345 14-35 year old residents in eight (8) villages in rural Limpopo. Married participants (OR 0.53 [95%CI 0.28 – 1.00]), those from poor (OR 0.49 [95%CI 0.28-0.85]) and less poor households (0.38 [95%CI 0.21-0.70]) are less likely to contract HIV infection. Noteworthy from these analyses also is the increased risk for HIV infection seen among female participants, those not currently schooling (OR 1.9 [95%CI 1.2 – 3.3]) and non-South African citizens (OR 5.18 [95%CI 1.04-25.8]). Conclusion: Women, out-of school youths and non South African citizens are shown to be high-risk population groups for HIV infection. HIV prevention programs that target identified vulnerable population groups and increased social support for the family may contribute to mitigating the spread of HIV in rural South Africa.