The Effect of Ignoring Statistical Interactions in Regression Analyses Conducted in Epidemiologic Studies: An Example with Survival Analysis Using Cox Proportional Hazards Regression Model

Objective: To demonstrate the adverse impact of ignoring statistical interactions in regression models used in epidemiologic studies. Study design and setting: Based on different scenarios that involved known values for coefficient of the interaction term in Cox regression models we generated 1000 samples of size 600 each. The simulated samples and a real life data set from the Cameron County Hispanic Cohort were used to evaluate the effect of ignoring statistical interactions in these models. Results: Compared to correctly specified Cox regression models with interaction terms, misspecified models without interaction terms resulted in up to 8.95 fold bias in estimated regression coefficients. Whereas when data were generated from a perfect additive Cox proportional hazards regression model the inclusion of the interaction between the two covariates resulted in only 2% estimated bias in main effect regression coefficients estimates, but did not alter the main findings of no significant interactions. Conclusions: When the effects are synergic, the failure to account for an interaction effect could lead to bias and misinterpretation of the results, and in some instances to incorrect policy decisions. Best practices in regression analysis must include identification of interactions, including for analysis of data from epidemiologic studies

Multicollinearity in Regression Analyses Conducted in Epidemiologic Studies

The adverse impact of ignoring multicollinearity on findings and data interpretation in regression analysis is very well documented in the statistical literature. The failure to identify and report multicollinearity could result in misleading interpretations of the results. A review of epidemiological literature in PubMed from January 2004 to December 2013, illustrated the need for a greater attention to identifying and minimizing the effect of multicollinearity in analysis of data from epidemiologic studies. We used simulated datasets and real life data from the Cameron County Hispanic Cohort to demonstrate the adverse effects of multicollinearity in the regression analysis and encourage researchers to consider the diagnostic for multicollinearity as one of the steps in regression analysis

Clinical diagnosis of Plasmodium falciparum among children with history of fever, Sindh, Pakistan

Objective: To identify clinical predictors for malaria and develop a clinical algorithm to more accurately identify malaria from non-malaria cases.Methods: Four hundred thirty eight children aged 6-120 months attending the rural health center between August 15 and October 5, 1997, in Jhangara town of district Dadu, Sindh were recruited. A standard questionnaire was used to record symptoms and duration of child\u27s illness. Each child was physically examined, had their axillary temperature measured, and blood samples were collected from which Giemsa stained thick and thin blood films were prepared and examined for presence of Plasmodium parasites. The sensitivity and specificity of several candidate algorithms for parasitemia were evaluated using various combinations of identified predictors.Results: Twenty-six of 438 children (6%) were slide positive for malaria. An algorithm comprised of fever 3 days duration and (absence of cough or having rigors) had 100% sensitivity and 63% specificity for detecting P. falciparum.CONCLUSION: In this low malaria prevalence region, restricting the diagnosis of malaria to persons who had \u3e3 days of fever and absence of cough or rigors, remained highly sensitive but was more specific than current practice. If validated prospectively, this algorithm could reduce misdiagnosis and mis-treatment

Frequency and determinants of vaginal infection in postpartum period: a cross sectional survey from low socioeconomic settlements, Karachi, Pakistan

Objective: To determine the frequency and factors associated with perceived vaginal infections among married women in their postpartum period. Methods: A cross-sectional study was conducted from July 2000 to October 2000 in five squatter settlements of Karachi, Pakistan. These squatter settlements were selected on the basis of an existing surveillance system run by female community health workers for maternal and child healthcare which identified women who had delivered 42-56 days prior to the date of interview. Vaginal infection was considered present when a mother perceived foul smelling vaginal discharge during the postpartum period. Mothers were interviewed to gain insight into socioeconomic and demographic variables, materials used to staunch lochia, duration of labour, personal and perineal hygiene and past obstetric history. Results: A total of 525 women were interviewed. The estimated prevalence of perceived vaginal infection was 5.1%. Factors associated with perceived vaginal infections included, delivery conducted by a non-medical personnel (AOR 3.5, CI 1.3-9.5) and use of unhygienic cloth or cotton for staunch of lochia (AOR 2.7, CI 1.1-6.2). Conclusion: Among women who reported perceived vaginal infection, a higher proportion were delivered by non-medical personnel, and used unhygienic material (cloth or cotton) for staunch of lochia as compared to women who did not perceive vaginal infection. We recommend deliveries to be conducted by trained personnel and provision of health education for persons who conduct delivery and women to use hygienic material for staunch of lochia during post partum period (JPMA 56:99;2006)

Undiagnosed Diabetes and Pre-Diabetes in Health Disparities

Globally half of all diabetes mellitus is undiagnosed. We sought to determine the extent and characteristics of undiagnosed type 2 diabetes mellitus and pre-diabetes in Mexican Americans residing in the United States. This disadvantaged population with 50% lifetime risk of diabetes is a microcosm of the current pandemic. We accessed baseline data between 2004 and 2014 from 2,838 adults recruited to our Cameron County Hispanic Cohort (CCHC); a two-stage randomly selected \u27Framingham-like\u27 cohort of Mexican Americans on the US Mexico border with severe health disparities. We examined prevalence, risk factors and metabolic health in diagnosed and undiagnosed diabetes and pre-diabetes. Two thirds of this Mexican American population has diabetes or pre-diabetes. Diabetes prevalence was 28.0%, nearly half undiagnosed, and pre-diabetes 31.6%. Mean BMI among those with diabetes was 33.5 kg/m2 compared with 29.0 kg/m2 for those without diabetes. Significant risk factors were low income and educational levels. Most with diabetes had increased waist/hip ratio. Lack of insurance and access to health services played a decisive role in failure to have diabetes diagnosed. Participants with undiagnosed diabetes and pre-diabetes had similar measures of poor metabolic health similar but generally not as severe as those with diagnosed diabetes. More than 50% of a minority Mexican American population in South Texas has diabetes or pre-diabetes and is metabolically unhealthy. Only a third of diabetes cases were diagnosed. Sustained efforts are imperative to identify, diagnose and treat individuals in underserved communities

Severity of Child Autistic Symptoms and Parenting Stress in Mothers of Children with Autism Spectrum Disorder in Japan and USA: Cross-Cultural Differences

The purpose of this study was to compare the relationship between parenting stress and autistic symptom severity in the U.S. and Japan. Fifty-two U.S. and 51 Japanese mothers of children aged 2-12 with autism completed measures of parenting stress and child characteristics, including the parenting stress index (PSI), the social communication questionnaire (SCQ), and social responsiveness scale-2 (SRS-2). There was a nonlinear relationship between the child\u27s autistic symptom severity and parenting stress in both countries. We also found some cultural differences: in the parent domain, the relationships between children\u27s SCQ scores and PSI scores differed significantly between the U.S. and Japan. Our findings suggest that autistic severity symptom scores may reflect cross-cultural differences in parenting beliefs, views toward autism, and response styles for evaluating children\u27s behavior. The findings also suggest that parents need support regardless of the child\u27s autism severity, including those with mild to moderate symptoms. Expanding on this line of research and understanding cultural influences on parenting stress may help service providers and agencies offer more culturally sensitive services, parent-education courses, and intervention programs

Construct Validity For the Self-Reported Competency and Sub-Construct associated Characteristics of Romanian Physicians in autism Spectrum Disorder

BACKGROUND: Lack of physicians\u27 knowledge regarding mental health, including Autism Spectrum Disorder (ASD) could have adverse effects on affected individuals\u27 health and quality of life. The purpose of this study was to provide construct validity for a modified questionnaire in order to determine the self-reported competency for underlying sub-constructs in ASD, make inferences on perceived competence in ASD based on a sample of Romanian physicians, and identify physicians\u27 characteristics associated with these sub-domains of competency. METHODS: For this survey, we modified a questionnaire that was used in Pakistan and Turkey, and administered it to a sample of 383 practicing physicians in Romania to assess their perceived competency regarding ASD. Exploratory factor analysis on 12 knowledge questions revealed five sub-domains: stigma, potential causes, children\u27s behavior, misconceptions, and educational needs associated with ASD knowledge. Using General Linear Models, we determined physicians\u27 characteristics that predict the total competency score and various competency sub-scores. RESULTS: Seventy-five percent of the responding physicians were female and 30% had over 30 years practicing medicine. The majority (73-94%) of physicians have correctly responded to some basic questions regarding knowledge about ASD. We also found that younger physicians were more knowledgeable about potential causes of ASD than older physicians (Adjusted Mean Score (AMS): 2.90 vs. 2.18, P \u3c 0.01), while older physicians knew more about the behavior of children with ASD (AMS: 0.64 vs. 0.37, P = 0.02). We found a significant interaction (P \u3c 0.01) between television as source of ASD knowledge and city where the clinic is located in relation to knowledge of the physicians regarding stigma related to ASD. However, the total score was not associated with the variables associated with sub-domains. CONCLUSION: Using factor analysis, we demonstrated construct validity of five sub-domains related to Romanian physicians\u27 knowledge about ASD that include stigma, potential causes, behavior in ASD children, special education needs, and misconceptions related to ASD. The lack of significant association of the knowledge of physicians on ASD neither with the Psychiatry nor the Pediatric ward rotations at medical school may support the need for improving the curriculum on ASD in Romanian medical schools

Association of Total and Differential White Blood Cell Counts to Development of Type 2 Diabetes in Mexican Americans in Cameron County Hispanic Cohort

Objective: To evaluate the relationship between total and differential White Blood Cell (WBC) counts with time to transition to type 2 diabetes in Mexican Americans using prospective data from the Cameron County Hispanic Cohort (CCHC). Results: Multivariable Cox proportional hazards regression models revealed that obese Mexican-American cohort participants whose total WBC or granulocyte count increased over time had 1.39 and 1.35 times higher risk respectively of transition to type 2 diabetes when compared to overweight participants. The granulocyte or total WBC count in participants with BMI≥35 were significant risk factors for transition to type 2 diabetes. Conclusions: Increased total WBC and WBC differential counts, particularly lymphocytes and granulocytes, are associated with risk of transition to type 2 diabetes in obese Mexican Americans, after adjusting for other potential confounders. Screening and monitoring the WBC counts, including lymphocytes and granulocytes can help with monitoring potential transition to type 2 diabetes

DataGauge: A Practical Process for Systematically Designing and Implementing Quality Assessments of Repurposed Clinical Data

The well-known hazards of repurposing data make Data Quality (DQ) assessment a vital step towards ensuring valid results regardless of analytical methods. However, there is no systematic process to implement DQ assessments for secondary uses of clinical data. This paper presents DataGauge, a systematic process for designing and implementing DQ assessments to evaluate repurposed data for a specific secondary use. DataGauge is composed of five steps: (1) Define information needs, (2) Develop a formal Data Needs Model (DNM), (3) Use the DNM and DQ theory to develop goal-specific DQ assessment requirements, (4) Extract DNM-specified data, and (5) Evaluate according to DQ requirements. DataGauge\u27s main contribution is integrating general DQ theory and DQ assessment methods into a systematic process. This process supports the integration and practical implementation of existing Electronic Health Record-specific DQ assessment guidelines. DataGauge also provides an initial theory-based guidance framework that ties the DNM to DQ testing methods for each DQ dimension to aid the design of DQ assessments. This framework can be augmented with existing DQ guidelines to enable systematic assessment. DataGauge sets the stage for future systematic DQ assessment research by defining an assessment process, capable of adapting to a broad range of clinical datasets and secondary uses. Defining DataGauge sets the stage for new research directions such as DQ theory integration, DQ requirements portability research, DQ assessment tool development and DQ assessment tool usability