published_or_final_version / Statistics and Actuarial Science / Master / Master of Philosophy

A descriptive study was conducted comparing the blood pressure and heart rate responses to position change among hypovolemic and normovolemic subjects. A convenience sample of 32 men and women from an emergency room with complaints of diarrhea, vomiting, vaginal or rectal bleeding for $\ge$12 hours duration were recruited. The normovolemic group consisted of a convenience sample of 30 men and women from the community. Data analysis included a mixed design analysis of variance. Compared to supine baseline measurements, between group changes in the systolic, diastolic, and mean arterial blood pressure were not statistically significant (p $>$.05). Once the subject stood, heart rate increased statistically significant in both groups (p $<$.05). The data suggest orthostatic hypotension can be considered when the supine resting heart rate is $\ge$87 beats per minute, and if upon standing, heart rate increases by $\ge$19.33 or is $\ge$110 beats per minute. Heart rate measurements should be taken at one minute after standing.

There are several methods of analysing time-to-event data. These include nonparametric approaches such as Kaplan-Meier estimation and parametric approaches such as regression modeling. Parametric regression modeling involves specifying the distribution of the survival time of the individuals, which are commonly chosen to be either exponential, Weibull, log- normal, log-logistic or gamma distributed. Another well known model that does not require assumptions about the hazard function to be made is the Cox proportional hazards model. However, there may be deviations from proportional hazards which may be explained by unaccounted random heterogeneity. In the early 1980s, a series of studies showed concern with the possible bias in the estimated treatment e®ect when important covariates are omitted. Other problems may be encountered with the traditional proportional hazards model when there is a possibility of correlated data, for instance when there is clustering. A method of handling these types of problems is by making use of frailty modeling. Frailty modeling is a method whereby a random e®ect is incorporated in the Cox pro- portional hazards model. While this concept is fairly simple to understand, the method of estimation of the ¯xed and random e®ects becomes complicated. Various methods have been explored by several authors, including the Expectation-Maximisation (EM) algorithm, pe- nalized partial likelihood approach, Markov Chain Monte Carlo (MCMC) methods, Monte Carlo EM approach and di®erent methods using Laplace approximation. The lack of available software is problematic for ¯tting frailty models. These models are usually computationally extensive and may have long processing times. However, frailty modeling is an important aspect to consider, particularly if the Cox proportional hazards model does not adequately describe the distribution of survival time. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

This thesis presents perspectives of men regarding abortion, contraceptive use and sexuality. Contrary to what we had expected, men expressed anxiety over abortion and contraceptive use, not because the issues concerned women’s health, but rather because men associated them with extramarital sexual activity they thought women were concealing. To understand the meanings of sexuality and factors shaping these meanings appeared to be a necessary step in promoting women’s health. We thus included in the study participants with different characteristics including men, women and adolescents, and used a variety of qualitative methods to explore in-depth these issues. Men’s anxiety over wives’ sexuality seemed to be exacerbated by their separation from the family through labour migration, and their inability to play the expected role of the family breadwinner. The men described using different strategies to ensure their wives did not use contraceptives. Men’s perspectives and the related dynamics seem therefore to be a manifestation of contradictory experiences of gender power within contexts of spousal separation. The thesis also illuminates the paradoxical situation of adolescents and adolescent sexual and reproductive health. As guardians, the men described how they are intolerant to premarital sex and pregnancy, which might threaten the expected bride wealth from the marriage of a daughter or sister. They therefore respond with violence. Ironically, information or service which would enable unmarried girls to prevent pregnancy is also denied. This is so in spite of the great concern by families over premarital pregnancy, and common knowledge that young girls are sexually abused by adult men. The men and boys described the pressure they exert on the girls for sex, but also how they then blame the girls for deliberately becoming pregnant in order to trap them into marriage. The boys are nevertheless anxious about pregnancy also for fear of family violence and the threat of being forced to terminate schooling. The girls expressed feeling trapped between the violence from guardians and partners, a situation which may lead to unsafe abortion. The silence, denial and violence imply the young people generally cannot discuss sexual abuse or abortion with parents, or seek health care when needed. Rather, sexually transmitted infections may be ndured or even self-treated, and abortion sought in silence. Preventive actions such as condom use are similarly difficult for the youth. The knowledge the youth may have about AIDS may also simply become a burden when room for applying it is limited. This thesis challenges public health promotion approaches that assume firstly a universal manifestation of gender power, and secondly ability of individuals to effect behaviour change once provided with information regardless of contextual factors. Whether in AIDS education or involvement of men in sexual and reproductive health, understanding social contexts and dynamics, and identities and experiences within these contexts is crucial.

FOOD HABITS, DIETARY INTAKE AND NUTRITIONAL STATUS DURING ECONOMIC CRISIS AMONG PREGNANT WOMEN IN CENTRAL JAVA, INDONESIA Th. Ninuk Sri Hartini, Epidemiology and Public Health Sciences, Dept. of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden; Community Health and Nutrition Research Laboratories, Gadjah Mada University, Jogjakarta, Indonesia; Nutrition Academy, Ministry of Health, Jogjakarta, Indonesia ABSTRACT Objectives: The overall objective of this thesis was to study the effect of the economic crisis on food habits, dietary intake and nutritional status among pregnant women in Purworejo District, Central Java, Indonesia. Subjects and methods: Since 1994, the Community Health and Nutrition Research Laboratories (CHN-RL), Gadjah Mada University, Jogjakarta, Indonesia have operated a surveillance system in Purworejo District, Central Java, Indonesia. Between 1996 and 1998, a monthly monitoring of new pregnancies took place within the surveillance system. This project included a detailed evaluation of dietary intake during pregnancy. Each trimester six repeated 24-hour recalls were conducted on 450 pregnant women. Weight and mid-upper arm circumference (MUAC) were measured monthly, height and serum ferritin concentration was measured once. Here, the dietary intake and nutritional status of the women during the second trimester are evaluated in relation to the emergence of the economic crisis, that started in 1997. Women were classified into four socio-economic groups. A computer program (Inafood) was developed to calculate nutrient intake. To support the quantitative results, a qualitative study was carried out between January and June 1999. Focus group discussions were held with four groups of women, in-depth interviews with 16 women, three traditional birth attendants and four midwives, and observations were carried out with four women. Here, food habits and coping strategies in relation to the economic crisis were explored. Results: Before the crisis, more than 80% of the pregnant women had inadequate energy and 40% had inadequate protein and vitamin A intake. All women had inadequate calcium and iron intake. The food intake consisted of rice, nuts and pulses and vegetables, meaning that it was mainly plant-based food. Rice behaved as a strongly inferior good in economic term, meaning that its consumption increased in spite of its price increase. Rice remained an important supplier of energy, protein and carbohydrates also during the crisis. Especially, rural, poor women with access to rice fields increased their rice intake and decreased their intake of non-rice staple foods. Reasons for the continued rice intake included the women had been accustomed to eating rice since they were born and that cooking methods for non-rice staple foods were difficult. The intake of animal food was low initially and decreased further during the economic crisis. Rich women decreased their intake of fat. The intake of nuts and pulses and vegetables increased for most groups. Nuts and pulses were an important supplier of calcium and iron, and vegetables were an important supplier of vitamin A. The rural, poor women with access to rice fields kept their food taboos also during the crisis. Rich women were able to maintain a good nutrient intake during the crisis, although fat intake decreased. Also, urban poor and rural, poor, landless women had an increased intake “during crisis” because relatives and neighbour provided some foods and perhaps also because of the government support programme. Conclusion: Before the crisis, energy and nutrient intake of pregnant women were inadequate. The food pattern of the women was predominately plant-based. Rich women were able to maintain a good nutrient intake during the crisis, although fat intake decreased. Rural poor women with access to rice fields had a higher rice intake than other groups throughout the crisis. Urban poor and rural poor, landless women experienced a decreased intake of most nutrients in the transition period but an increased intake during the crisis, reflecting government intervention and support from relatives and neighbours. The latter, however, is not sustainable. Thus, vulnerable groups are at risk of developing nutritional deficiencies without food support programmes. Key words: Food intake, nutrient intake, nutritional status, food pattern, pregnancy, food habits, coping strategies, economic crisis, Indonesia.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Statistics and Actuarial Science / Master / Master of Philosophy

Background: Iron and zinc are difficult to provide in sufficient amounts in complementary foods to infants world-wide, resulting in high prevalence of both iron and zinc deficiency. These deficiency states cause anemia, delayed neurodevelopment, impaired growth, and increased susceptibility to infections such as diarrhea and respiratory infections. Design: Two different intervention strategies; reduction of a possible inhibitor of iron and zinc absorption, i.e. phytate, or supplementation with iron and zinc, were applied to two different populations in order to improve iron and zinc nutrition: In a high-income population (Umeå, Sweden), the amount of phytate in commonly consumed infant cereals was reduced. Healthy, term infants (n=300) were at 6 mo of age randomized to phytate-reduced infant cereals, conventional infant cereals, or infant formula and porridge. In a low income population (Purworejo, Indonesia), daily iron and zinc supplementation was given. Healthy, term infants (n=680) were at 6 mo randomized to supplementation with iron, zinc, a combination of iron and zinc, or placebo. Blood samples, anthropometrical measurements, and data on infant neurodevelopment and morbidity were collected. Also, in the Swedish study, detailed information on the dietary intake was recorded. Results: In the Swedish study, the reduction of phytate had little effect on iron and zinc status, growth, development or incidence of diarrhea or respiratory infections, possibly due to the presence of high contents of ascorbic acid, which may counteract the negative effects of phytate. In the Indonesian study, significant negative interaction between iron and zinc was evident for several of the outcomes; Hb and serum ferritin improved more in the iron only group compared to placebo or the combined iron and zinc group. Further, supplementation with iron alone improved infant psychomotor development and knee-heel length, whereas supplementation with zinc alone improved weight and knee-heel length compared to placebo. Combined iron and zinc supplementation did decrease the prevalence of iron deficiency anemia and low serum zinc, but had no other positive effects. Vomiting was more common in the combined group. Analyses of dietary intake from the Swedish study showed that dietary iron intake in the 6-11 mo period was significantly associated with Hb, but not serum ferritin at 9 and 12 mo, whereas the opposite was true in the 12-17 mo period, i.e. dietary iron intake was significantly associated with serum ferritin, but not Hb at 18 mo. Conclusions: The phytate content of commercial infant cereals does not seem to contribute to poor iron and zinc status of Swedish infants as feared. However, the current definitions of iron and zinc deficiency in infancy may overestimate the problem, and a change in the recommended cutoffs is suggested. These studies also indicate that dietary iron is preferably channeled towards erythropoiesis during infancy, but to an increasing amount channeled towards storage in early childhood. This suggests that in evaluating dietary programs, Hb may be superior in monitoring response to dietary iron in infancy, whereas S-Ft may respond better later in childhood. However, as shown in this study, increasing Hb may not necessarily be an indicator of iron deficiency, as more dietary iron increased Hb regardless of iron status. In the low-income setting combined supplementation with iron and zinc resulted in significant negative interaction. Thus, it is not possible to recommend routine iron-zinc supplementation at the molar concentration and mode used in this study. It is imperative that further research efforts are focused at finding cost-effective strategies to prevent iron and zinc deficiency in low-income populations.

A clinical trial is considered in which two treatments are to be compared. Treatment allocation schemes are usually designed to assign approximately equal numbers of patients to each treatment. The purpose of this thesis is to investigate the efficiency of estimation and the effect of instability in the response variable for allocation schemes which are aimed at reducing the number of patients who receive the inferior treatment. The general background to outcome-dependent allocation schemes is described in Chapter 1. A discussion of ethical and practical problems associated with these methods is presented together with brief details of actual trials conducted. In Chapter 2, the response to treatment is Bernoulli and the trial size is fixed. A simple method for estimating the treatment difference is proposed. Simulation results for a selection of allocation schemes indicate that the effect of instability upon the performance of the schemes can sometimes be substantial. A decision-theory approach is taken in Chapter 3. The trial is conducted in a number of stages and the interests of both the patients in the trial and those who will be treated after the end of the trial are taken into account. Using results for conditional normal distributions, analytical results are derived for estimation of the treatment difference for both a stable and an unstable normal response variable for three allocation schemes. Some results for estimation are also given for other responses. The problem of sequential testing is addressed in Chapter 4. With instability in the response variable, it is shown that the error probabilities for the test for a stable response variable can be approximately preserved by using a modified test statistic with appropriately-widened stopping boundaries. In addition, some recent results for estimation following sequential tests are outlined. Finally, the main conclusions of the thesis are highlighted in Chapter 5.

For reasoning under uncertainty the Bayesian network has become the representation of choice. However, except where models are considered 'simple' the task of construction and inference are provably NP-hard. For modelling larger 'real' world problems this computational complexity has been addressed by methods that approximate the model. The Naive Bayes classifier, which has strong assumptions of independence among features, is a common approach, whilst the class of trees is another less extreme example. In this thesis we propose the use of an information theory based technique as a mechanism for inference in Singly Connected Networks. We call this a Mutual Information Measure classifier, as it corresponds to the restricted class of trees built from mutual information. We show that the new approach provides for both an efficient and localised method of classification, with performance accuracies comparable with the less restricted general Bayesian networks. To improve the performance of the classifier, we additionally investigate the possibility of expanding the class Markov blanket by use of a Wrapper approach and further show that the performance can be improved by focusing on the class Markov blanket and that the improvement is not at the expense of increased complexity. Finally, the two methods are applied to the task of diagnosing the 'real' world medical domain, Acute Abdominal Pain. Known to be both a different and challenging domain to classify, the objective was to investigate the optiniality claims, in respect of the Naive Bayes classifier, that some researchers have argued, for classifying in this domain. Despite some loss of representation capabilities we show that the Mutual Information Measure classifier can be effectively applied to the domain and also provides a recognisable qualitative structure without violating 'real' world assertions. In respect of its 'selective' variant we further show that the improvement achieves a comparable predictive accuracy to the Naive Bayes classifier and that the Naive Bayes classifier's 'overall' performance is largely due the contribution of the majority group Non-Specific Abdominal Pain, a group of exclusion.