The Targeted Maximum Likelihood estimation to estimate the causal effects of the previous tuberculosis treatment in Multidrug-resistant tuberculosis in Sudan.

INTRODUCTION: This study used Targeted Maximum Likelihood Estimation (TMLE) as a double robust method to estimate the causal effect of previous tuberculosis treatment history on the occurrence of multidrug-resistant tuberculosis (MDR-TB). TMLE is a method to estimate the marginal statistical parameters in case-control study design. The aim of this study was to estimate the causal effect of the previous tuberculosis treatment on the occurrence of MDR-TB using TMLE in Sudan. METHOD: A case-control study design combined with TMLE was used to estimate parameters. Cases were MDR-TB patients and controls were and patients who cured from tuberculosis. The history of previous TB treatment was considered the main exposure, and MDR-TB as an outcome. A designed questionnaire was used to collect a set of covariates including age, time to reach a health facility, number of times stopping treatment, gender, education level, and contact with MDR-TB cases. TMLE method was used to estimate the causal association of parameters. Statistical analysis was carried out with ltmle package in R-software. Result presented in graph and tables. RESULTS: A total number of 430 cases and 860 controls were included in this study. The estimated risk difference of the previous tuberculosis treatment was (0.189, 95% CI; 0.161, 0.218) with SE 0.014, and p-value (<0.001). In addition, the estimated risk ratio was (16.1, 95% CI; 12.932, 20.001) with SE = 0.014 and p-value (<0.001). CONCLUSION: Our findings indicated that previous tuberculosis treatment history was determine as a risk factor for MDR-TB in Sudan. Also, TMLE method can be used to estimate the risk difference and the risk ratio in a case-control study design.

Network meta-analysis of palliative treatments in patients with esophageal cancer.

We aimed to compare available palliative treatments in terms of survival and to rank these treatments for esophageal cancer. Web of Science, Medline, Scopus, Cochrane Library and Embase were searched. The risk of bias was judged using Cochrane's tools. Statistical heterogeneity was assessed using the Chi2 test and was quantified by I2. The results were summarized using the hazard ratio (HR). The rank probability for each treatment was calculated using the p-score. Nineteen RCTs met the eligibility criteria for this study. Treatments formed three networks including networks A, B, and C. The Ultraflex stent (p-score = 0.93), irradiation stent (p-score = 0.89), and thermal ablative therapy (p-score = 0.85) were the first ranking treatments in networks A, B, and C, respectively. Based on the results of this network meta-analysis, it appears that the ultraflex stent, the irradiation stent, and thermal ablative therapy are the better treatments among the networks.

Factors associated with quality of life among joint and nuclear families: a population-based study.

BACKGROUND: Advantages and disadvantages associated with joint and nuclear family systems can affect quality of life (QOL). However, there is scarcity of literature about QOL among joint and nuclear family systems. This study aimed to assess the factors associated with QOL in joint and nuclear family systems. METHODS: We conducted a population based cross sectional study in all 52 Union Councils (UCs) of District Abbottabad, Khyber Pakhtunkhwa province, Pakistan from March 2015 to August 2015. Multistage cluster sampling technique was used to select participants from both nuclear and joint family houses. The validated Urdu version of World Health Organization Quality of Life Questionnaire-Brief Version (WHOQOL-BREF) was used to assess quality of life among participants. Univariate and multivariate analyses were performed to explore the associations of different socio demographic variables with QOL among both family systems. Also a multilevel linear regression using backward analysis to obtain final model for each domain was performed to find out the variables that are associated with QOL score in each of family systems. RESULTS: A total of 2063 participants were included in this study (51.0% joint family, 49.0% nuclear family) with the response rate of 97.4%. In multiple linear regression analysis of each domain for joint and nuclear family systems, rural residence compared to urban (p < 0.001), being female (p < 0.001), older age (p < 0.001), having comorbidity (p < 0.001) and lower socioeconomic status (p < 0.001) were found to be a strong predictor of poorer QOL. Furthermore, social capital (p < 0.001) had a positive effect on joint and nuclear family QOL scores. CONCLUSION: This study was the first of its kind which determined the factors of QOL in joint and nuclear families using the validated Urdu version of WHOQOL-BREF in Pakistan. Male gender, urban residence, younger age, higher socioeconomic status and social capital were positive predictors of QOL score while older age and presence of illness were associated with lower QOL scores among both family systems.

Treatment-related complications in patients with esophageal cancer: A systematic review and network meta-analysis.

BACKGROUND: The aim of this review was to compare the available treatments of esophageal cancer, in terms of pulmonary, cardiovascular complications, anastomotic leakage, and esophagitis after treatment in patients with esophageal squamous cell carcinoma (SCC). METHODS: Medline, Web of Science, Scopus, the Cochrane Library and Embase were searched. The randomized controlled trials (RCT) that had compared the treatment -related complications of treatments for esophageal SCC were included. We included 39 randomized control trials in a network meta-analysis. The Chi2-test was used to assess of heterogeneity. The loop-specific and design-by-treatment interaction methods were used for assessment of consistency assumption. The risk ratio with 95% confidence interval (CI) was used to report the effect-sizes in the network meta-analysis. RESULTS: The pulmonary complication, cardiac complication, anastomotic leakage, and esophagitis were reported in 31, 11, 17, and 15 RCTs respectively. Video-assisted thoracoscopy + laparoscopy (VATS) was rank as the first and second treatment in terms of lower risk for pulmonary complication and anastomotic leakage. There was no statistically significant difference between treatments in terms of lower risk of cardiovascular complications. However, Surgery + Cisplatin + Fluorouracil (SCF) was ranked as better treatment. 3-dimensional conformal radiotherapy + Docetaxel + Cisplatin (3DCRTDC) was the best treatment in terms of lower risk for esophagitis. CONCLUSION: According to the results of this study, it seems the risk of pulmonary, cardiovascular, anastomotic leakage and esophagitis complications for VATS, SCF, surgery + radiotherapy (SRT), and 3DCRTDC was lower than other treatments respectively in the networks.

Effect of Social Distancing on COVID-19 Incidence and Mortality in Iran Since February 20 to May 13, 2020: An Interrupted Time Series Analysis.

BACKGROUND AND OBJECTIVE: Numerous actions have been taken to control the COVID-19 pandemic and reduce their morbidity and mortality. One of the most important measures in this regard is social distancing. However, there is limited evidence on the effectiveness of social distancing on COVID-19 incidence and mortality. Thus, the current study aimed to assess the effectiveness of social distancing measures on the COVID-19 incidence and mortality in Iran. MATERIALS AND METHODS: In the current quasi-experimental study, we evaluated the daily incidence cases and the number of deaths of COVID-19 in Iran before and after the implementation of social distancing measures. The segmented regression model was used to analyze the data. We also performed the interrupted time series (ITS) analysis using Newey ordinary least squares (OLS) regression-based methods. RESULTS: After the implementation of social distancing, the trend of both daily new cases and deaths due to COVID-19 was decreasing [(ß = -1.70 (95% CI = [-2.30 - -1.10; P < 0.001])) and (ß = -0.07 (95% CI = [-0.10 - -0.05; P < 0.001], respectively))]. CONCLUSION: Social distancing along with other public health interventions could reduce the morbidity and mortality of COVID-19 to some degrees, and it seems to be crucial to control the pandemic.

Alarm Thresholds for Pertussis Outbreaks in Iran: National Data Analysis.

OBJECTIVES: The purpose of the current study was to determine the upper threshold number of cases for which pertussis infection would reach an outbreak level nationally in Iran. METHODS: Data on suspected cases of pertussis from the 25th February 2012 to the 23rd March 2018 from the Center for Disease Control and Prevention in Iran was used. The national upper threshold level was estimated using the exponentially weighted moving average (EWMA) method and the Poisson regression method. RESULTS: In total, 2,577 (33.6%) and 1,714 (22.3%) cases were reported in the Spring and Summer respectively. There were 1,417 (18.5%) and 1,971 (25.6%) cases reported in the Autumn and Winter, respectively. The overall upper threshold using the EWMA and the Poisson regression methods, was estimated as a daily occurrence of 8 (7.55) and 7.50 (4.48-11.06) suspected cases per 10,000,000 people, respectively. The daily seasonal thresholds estimated by the EWMA and the Poisson regression methods were 10, 7, 6, 8 cases and 10, 7, 7, 9 cases for the Spring, Summer, Autumn, and Winter, respectively. CONCLUSION: The overall and seasonal estimated thresholds by the 2 methods were similar. Therefore, the estimated thresholds of 6-10 cases in a day, per 10,000,000 people could be used to detect pertussis outbreaks and epidemics by health policymakers.

Exploring spatial dependencies in the prevalence of childhood diarrhea in Mozambique using global and local measures of spatial autocorrelation.

Background: Diarrhea in children under 5 years is generally considered as an important public health problem and the major cause of childhood morbidity and mortality in Sub-Saharan Africa. The purpose of this study was to present exploratory spatial data analyses to identify spatial clusters and outliers in the prevalence of childhood diarrhea in Mozambique. Methods: Using data from 2011 Mozambique Demographic and Health Survey, we calculated the prevalence of childhood diarrhea on the district level. Two exploratory spatial data analyses methods were applied, namely, global and local Moran's I statistics, providing spatial autocorrelation and spatial clusters/outlier in the prevalence of childhood diarrhea, respectively. Results: Choropleth mapping and global Moran's I statistics showed that the prevalence of childhood diarrhea has clustered distribution across the study area. A local Moran's I index revealed spatial clusters within the province of Tete, Gaza, Cabo Delgado, and Zambezia. However, spatial outliers were confined within Sofala province. Conclusion: The exploratory spatial data analyses showed various spatial clustering and outliers present in the prevalence of childhood diarrhea, indicating interventions needed in targeted regions.

The comparative performance of wavelet-based outbreak detector, exponential weighted moving average, and Poisson regression-based methods in detection of pertussis outbreaks in Iranian infants: A simulation-based study.

BACKGROUND: Early detection of outbreaks of transmissible diseases is essential for public health. This study aimed to determine the performance of the wavelet-based outbreak detection method (WOD) in detecting outbreaks and to compare its performance with the Poisson regression-based model and exponentially weighted moving average (EWMA) using data of simulated pertussis outbreaks in Iran. METHOD: The data on suspected cases of pertussis from 25th February 2012 to 23rd March 2018 in Iran was used. The performance of the WOD (Daubechies 10 [db10] and Haar wavelets), Poisson regression-based method, and EWMA Compared in terms of timeliness and detection of outbreak days using the simulation of different outbreaks. In the current study, two simulations were used, one based on retrospectively collected data (literature-based) on pertussis cases and another one on a synthetic dataset created by the researchers. The sensitivity, specificity, false alarm, and false-negative rate, positive and negative likelihood ratios, under receiver operating characteristics areas, and median timeliness were used to assess the performance of the methods. RESULTS: In a literature-based outbreak simulation, the highest and lowest sensitivity, false negative in the detection of injected outbreaks were seen in db10, with sensitivity 0.59 (0.56-0.62), and Haar wavelets with 0.57 (0.54-0.60). In the researcher simulated data, the EWMA (K = 0.5) with sensitivity 0.92 (0.90-0.94) had the best performance. About timeliness, the WOD methods showed the best performance in the early warning of the outbreak in both simulation approaches. CONCLUSION: Performance of the WOD in the early alarming outbreaks was appropriate. However, this method would be best used along with other methods of public health surveillance.

Spatio-temporal analysis of Pertussis using geographic information system among Iranian population during 2012-2018.

Background: In spite of existing vaccination programs in many countries, outbreaks of pertussis are still reported. In Iran, the suspected and confirmed cases of pertussis are reported annually. Due to the lack of similar studies, the purpose of the current study was to determine the Spatio-temporal distribution of Pertussis using Geographic Information System (GIS) to identify high-risk areas in Iran during 2012-2018. Methods: In the current cross-sectional study, registered data in the department of vaccine-preventable diseases in the Iranian ministry of health were used. To assess the temporal trend, the Cochran-Armitage test was used. To show the spatial distribution and to identify hotspot areas, Choropleth map and Getis-Ord Gi statistics were used. All analyses performed by Arc.map10.5, Stata 15 and Excel 2010. Results: The incidence of suspect pertussis cases had an increasing trend but did not have a linear trend (p=0.06). Most of the cases happened in under 1 year infants (62.66%). The incidence of reported cases in northern areas was higher than in the Southern areas. The Zanjan had the most reported cases during the understudied period with a median of 7.63 reported cases per 100,000. The clustering of infection and hotspots were identified in northern areas of Iran including Qazvin, Qom, Markazi, and Hamadan. Conclusion: Our results showed that the cumulative incidence of reported cases is increasing. The northern provinces had the highest incidence of Pertussis. Therefore, the causes of this spatio-temporal pattern of pertussis should be determined. Also, supervision on vaccination programs in high-risk areas is recommended.

Low enrollment and high treatment success in children with drug-resistant tuberculosis in Ethiopia: A ten years national retrospective cohort study.

BACKGROUND: Limited evidence exists on the treatment outcome and factors that are associated with the duration from the initiation of treatment to death or treatment failure in children with drug resistant tuberculosis (DR-TB). Thus, we aimed to determine the proportion of treatment enrollment, status of treatment outcome and determine factors that are associated with the duration from treatment initiation to death or treatment failure in children treated for DR-TB in Ethiopia. METHODS: We conducted a retrospective cohort study in children younger than 15 years old who were treated for DR-TB from February 2009 to February 2019 in Ethiopia. We collected data on socio-demographic and clinical characteristics from clinical charts, registration books and laboratory result reports on 155 children. Proportion of enrollment to the treatment was calculated by dividing the total number of children who were receiving the treatment by the total number of DR-TB patients treated during the specified years. We used Cox proportional hazard models to determine factors that were associated with the duration from the beginning of the treatment to death or treatment failure. Data was analyzed using STATA version 14. RESULTS: Of the 3,478 DR-TB patients enrolled into the treatment and fulfilling our inclusion criteria during the past ten years, 155 (4.5%) were children. Of the 155 children, 75 (48.4%) completed the treatment and 51 (32.9%) were cured. Furthermore, 18 (11.6%) children were died, seven (4.5%) lost to follow up and treatment of four (2.6%) children was failed. The overall treatment success was 126 (81.3%). Age younger than 5 years old [Adjusted Hazard Ratio (AHR) = 3.2, 95%CI (1.2-8.3)], HIV sero-reactivity [AHR = 5.3, 95%CI (1.8-14.9)] and being anemic [AHR = 4.3, 95%CI (1.8-10.3)] were significantly associated with the duration from the enrollment into the treatment to death or treatment failure. CONCLUSION: In this study, the proportion of children enrolled into DR-TB treatment was lower than the proportion of adults enrolled to the treatment (4.5% in children versus 95.5% in adults) in last ten years. Our findings also suggest that children with DR-TB can be successfully treated with standardized long term regimen. Further prospective cohort study is required to investigate factors contributing to death or treatment failure.

Effect of maternal mental health during pregnancy on infant growth at six months of age in Suburban communities in South of Iran.

Background: Due to the controversial effects of mental health disorders during pregnancy on infant health, the present study aimed to evaluate the effect of gestational depression, stress, and anxiety on the growth of offspring at six months of age in disadvantaged communities in South of Iran. Methods: The sample comprised of 470 pregnant women (response rate=98%) who are participated in the Bandar Abbas Pregnancy Cohort study. Maternal mental health was measured by the DASS-21 questionnaire during pregnancy. Data on infant growth was collected based on infant`s growth chart at six months of age. The relative risk of suboptimal infant growth was calculated by Modified Poisson regression models at 5% significant level. Results: The prevalence of depression, anxiety, and stress was 19.0%, 26.1% and 6.5%, respectively. At six months of age, the mean (SD) of infant`s weight (gram), height (cm) and head circumference (cm) were 7287.30 (1019.85), 63.23 (5.62) and 41.39 (2.70), respectively. Compared to normal mothers, the risk of suboptimal weight at six months of age significantly increased by 71% in mothers who were classified as having depression (Adjusted RR: 1.71, 95% CI: 1.07, 2.09). The presence of anxiety significantly increased the risk of suboptimal height at six months of age by 43% (ARR: 1.43, 95% CI: 1.07, 1.92). There were no statistically significant effects of either depression anxiety or stress on the suboptimal head circumference at six months of age. Conclusion: Our results showed that mental health disorders of pregnant women might adversely influence the weight and height growth of offspring within the first six months of age. Screening protocols to early diagnose of mental health disorders during pregnancy, and to strict follow up of diagnosed cases postpartum are proposed.

Intermittent treatment interruption and its effect on multidrug resistant tuberculosis treatment outcome in Ethiopia.

Treatment interruption is one of the main risk factors of poor treatment outcome and occurrence of additional drug resistant tuberculosis. This study is a national retrospective cohort study with 10 years follow up period in MDR-TB patients in Ethiopia. We included 204 patients who had missed the treatment at least for one day over the course of the treatment (exposed group) and 203 patients who had never interrupted the treatment (unexposed group). We categorized treatment outcome into successful (cured or completed) and unsuccessful (lost to follow up, failed or died). We described treatment interruption by the length of time between interruptions, time to first interruption, total number of interruption episodes and percent of missed doses. We used Poisson regression model with robust standard error to determine the association between treatment interruption and outcome. 82% of the patients interrupted the treatment in the first six month of treatment period, and considerable proportion of patients demonstrated long intervals between two consecutive interruptions. Treatment interruption was significantly associated with unsuccessful treatment outcome (Adjusted Risk Ratio (ARR) = 1.9; 95% CI (1.4-2.6)). Early identification of patients at high risk of interruption is vital in improving successful treatment outcome.

Knowledge, attitude, and practice among mothers about newborn care in Sindh, Pakistan.

BACKGROUND: Each year nearly 7.7 million children under five years die around the world; out of which approximately 3.1 million of the newborns die during the neonatal period and almost all these (99%) deaths occur in the developing countries. According to the World Health Organization's estimation neonatal deaths account for 45% of the under-five deaths. More than one-third of these deaths occur in the first 24 h of birth, whereas three-quarter of the neonatal deaths takes place in the first seven days of birth. The purpose of this study is to assess the knowledge, attitude, and practices (KAP) among mothers about newborns' care and its related factors in district Badin Sindh province of Pakistan. METHODS: A community-based cross-sectional study was conducted from July 2017 to August 2017 to assess the Knowledge, Attitude, and Practices (KAP) in mothers regarding newborn care. A structured questionnaire was administered, after pretest, for data gathering through face to face interview. All survey participants were identified using multi-stage cluster sampling. A scoring system was used to calculate the level of KAP among participants. Independent sample t-test, ANOVA, and GLM were applied to identify the statistical difference between the means of various groups. RESULT: A total of 518 survey participants were interviewed. Among the study sample, more than half of the newborns were bathed within six hours of delivery. Around 50% started breastfeeding after 1 h of birth. A substantial proportion (45%) of mothers gave pre-lacteal feeding and 44.8% of them did not feed colostrum to their newborns. Among those who administered pre-lacteal to their newborn babies included animal/formula milk (15.4%), honey (24.5%) and fresh butter/ghee (5.2. %). Mothers with no education had less significant KAP score about newborn care as compared to those who had higher education (p < 0.05). CONCLUSION: This study revealed that high-risk factors such as immediate bathing, application of traditional substances on the cord, delayed initiation of breastfeeding, discarding colostrum and giving pre-lacteal feed to newborns were highly prevalent. This requires urgent attention of Maternal, Newborn and Child Health (MNCH) programs and health care delivery system to prevent harmful care practices and adopt healthy practices especially in the rural settings.

Level of satisfaction and its predictors among joint and nuclear family systems in District Abbottabad, Pakistan.

Background: Family system has been found to affect the satisfaction level among the family members. The objective of our study was to determine the satisfaction level and its predictors among joint and nuclear family systems in District Abbottabad, Pakistan. Methods: We conducted a population-based cross-sectional study in all 52 Union Councils (UCs) of District Abbottabad, Khyber Pakhtunkhwa province, Pakistan from March 2015 to August 2015. Multistage cluster sampling technique was used to select 2063 participants from both nuclear and joint family houses. Proportionate sampling was done for selecting mohalla from each UCs, and then subsequently households from respective mohalla's. Simple random sampling was done for selecting the 18 years and above-aged participant for the study. A structured demographic questionnaire was used to collect information from study participants. Univariate and multivariate logistic regression analysis was done to find out the predictors of satisfaction level among joint and nuclear family systems using SPSS version 20 A p-value of <0.05 was considered as significant. Results: Level of satisfaction was found to be higher among people living in the joint family system i.e., 87.5 % v/s 81 % (<0.001) compared to the nuclear family system. Multivariate regression analysis of nuclear family system showed that people having higher education level and higher socioeconomic status (SES) were more satisfied as compared to no education & low SES respectively. While, in the joint family system, only high SES was a significant predictor of satisfaction in the joint family system as compared to low SES. Conclusion: Our study reported a high level of satisfaction among joint and nuclear family systems in Pakistan. High education level and high SES were identified as important predictors of satisfaction among both systems.

Is hypothyroidism rare in multidrug resistance tuberculosis patients on treatment? A systematic review and meta-analysis.

BACKGROUND: Hypothyroidism is one of the adverse drug reactions that associated with Multidrug Resistant Tuberculosis (MDR-TB) medications. Extremely variable magnitude of hypothyroidism in MDR-TB patients has been reported from different parts of the world. However, there is no evidence that tried to estimate the pooled prevalence of hypothyroidism to confirm the rareness of hypothyroidism in MDR-TB patients on treatment. Therefore, we did a systematic review and meta-analysis to estimate the prevalence of hypothyroidism in MDR-TB patients on treatment, and to summarize the demographic and clinical characteristics of the patients. METHODS: We conducted a systematic review and meta-analysis on studies reported around the world on the prevalence of hypothyroidism in MDR-TB patients on treatment. We searched electronic databases: PubMed/Medline, EMBASE, CINAHL, Science Direct, Academic Search Complete and Google scholar for English language articles without limiting publication year. We also reviewed the bibliographies of relevant studies and conducted an electronic search for relevant conference abstracts. Eligible studies were cross-sectional and cohort studies that included at least five participants. We used a random-effects model to estimate the pooled prevalence of hypothyroidism. The registration number of this review study protocol is CRD42018109237. RESULTS: We included 30 studies and pooled data on a total of 6,241 MDR-TB patients. The crude prevalence of hypothyroidism was extremely heterogeneous. The pooled prevalence of hypothyroidism in MDR-TB patients on treatment was 17.0% (95% CI: 13.0-20.0). Ethionamide and para-aminosalicylic acid (PAS) were the most frequently reported drugs that associated with the occurrence of hypothyroidism. CONCLUSION: This review revealed that hypothyroidism is not a rare adverse drug reaction in MDR-TB patients on treatment. Ethionamide and PAS were the most frequently reported drugs that associated with the occurrence of hypothyroidism. Screening of hypothyroidism in MDR-TB patients on treatment is important while targeting patients on Ethionamide and PAS based treatment regimen.

Impact of Age at Menarche on Breast Cancer: The Assessment of Recall Bias.

BACKGROUND: Our aim was to determine the association between age at menarche (AAM) and breast cancer adjusted for recall bias (misclassification) in AAM. METHODS: We have used data provided from a case-control study conducted in Iran from 2005 to 2009. The cases and controls were frequency matched based on 5-year age groups and region of residence. First, logistic regression was conducted to estimate the odds ratio (OR) and second, Bayesian analysis was applied to estimate the ORs adjusted for misclassification. RESULTS: The study was conducted on 880 cases and 998 controls. In the assumption of no correction for recall bias on self-reported AAM, the OR was 1.36 (95% Credible Interval (0.98, 1.90). Based on a sensitivity value = 71% and a specificity value = 81% (the indices about the ratio of true recall of AAM) for the case and control groups (as the first scenario), the AAM ≤ 12 years of age was associated with a lower OR for breast cancer by 1.23 (95% Credible Interval: 0.50, 3.13). In the other scenario, with consideration of 100% sensitivity and specificity of self- reported AAM in the case group, and 71% and 81% sensitivity and specificity of the item in the control group, the related OR between breast cancer and AAM was found increased to 2.96 (95% Credible Interval: 0.75, 7.66). CONCLUSION: After adjustment for misclassification related to recall bias, this study provides evidence that the self-reported mode of AAM has a moderate impact on calculation of the OR.

Assessment of the risk factors associated with multidrug-resistant tuberculosis in Sudan: a case-control study.

OBJECTIVES: The emergence of multidrug-resistant tuberculosis (MDR-TB) is a major challenge for the global control of tuberculosis (TB). The aim of this study was to determine the risk factors associated with MDR-TB in Sudan. METHODS: This case-control study was conducted from May 2017 to February 2019. Patients newly diagnosed with MDR-TB were selected as cases, and controls were selected from TB patients who responded to first-line anti-TB drugs. A questionnaire was designed and used to collect data from study participants. Logistic regression was used to evaluate associations between risk factors and MDR-TB infection. The best multivariate model was selected based on the likelihood ratio test. RESULTS: A total of 430 cases and 860 controls were selected for this study. A history of previous TB treatment (adjusted odds ratio [aOR], 54.85; 95% confidence interval [CI], 30.48 to 98.69) was strongly associated with MDR-TB infection. We identified interruption of TB treatment (aOR, 7.62; 95% CI, 3.16 to 18.34), contact with MDR-TB patients (aOR, 5.40; 95% CI, 2.69 to 10.74), lower body weight (aOR, 0.89; 95% CI, 0.87 to 0.91), and water pipe smoking (aOR, 3.23; 95% CI, 1.73 to 6.04) as factors associated with MDR-TB infection. CONCLUSIONS: Previous TB treatment and interruption of TB treatment were found to be the main predictors of MDR-TB. Additionally, this study found that contact with MDR-TB patients and water pipe smoking were associated with MDR-TB infection in Sudan. More efforts are required to decrease the rate of treatment interruption, to strengthen patients' adherence to treatment, and to reduce contact with MDR-TB patients.

Geographically Weighted Regression Analysis: A Statistical Method to Account for Spatial Heterogeneity.

Ordinary linear regression (OLR) is one of the most common statistical techniques used in determining the association between the outcome variable and its related factors. This method determines the association that is assumed to be true for the whole study area - a global association. In the field of public health and social sciences, this assumption is not always true, especially when it is known that the relationship between variables varies across the study area. Therefore, in such a scenario, an OLR should be calibrated in a way to account for this spatial variability. In this paper, we demonstrate use of the geographically weighted regression (GWR) method to account for spatial heterogeneity. In GWR, local models are reported in which association varies according to the location accounting for the local variation in variables. This technique utilizes geographical weights in determining association between the outcome variable and its related factors. These geographical weights are relatively large (i.e. close to 1) for observations located near regression point than for the observations located farther from the regression point. In this paper, we demonstrated the application of GWR and its comparison with OLR using demographic and health survey (DHS) data from Tanzania. Here we have focused on determining the association between percentages of acute respiratory infection (ARI) in children with its related factors. From OLR, we found that the percentage of female with higher education had the largest significant association with ARI (P = 0.027). On the other hand, result from the GWR returned coefficients varying from -0.15 to -0.01 (P < 0.001) over the study area in contrast to the global coefficient from OLR model. We advocate that identifying significant spatially-varying association will help policymaker to recognize the local areas of interest and design targeted interventions.