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Shibata K, Hozawa A, Tamiya G, Ueki M, Nakamura T, Narimatsu H, Kubota I, Ueno Y, Kato T, Yamashita H, Fukao A, Kayama T. The confounding effect of cryptic relatedness for environmental risks of systolic blood pressure on cohort studies. Mol Genet Genomic Med 2013; 1:45-53. [PMID: 24498600 PMCID: PMC3893157 DOI: 10.1002/mgg3.4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 02/16/2013] [Accepted: 02/21/2013] [Indexed: 11/05/2022] Open
Abstract
The impact of cryptic relatedness (CR) on genomic association studies is well studied and known to inflate false-positive rates as reported by several groups. In contrast, conventional epidemiological studies for environmental risks, the confounding effect of CR is still uninvestigated. In this study, we investigated the confounding effect of unadjusted CR among a rural cohort in the relationship between environmental risk factors (body mass index, smoking status, alcohol consumption) and systolic blood pressure. We applied the methods of population-based whole-genome association studies for the analysis of the genome-wide single nucleotide polymorphism data in 1622 subjects, and detected 20.2% CR in this cohort population. In the case of the sample size, approximately 1000, the ratio of CR to the population was 20.2%, the population prevalence 25%, the prevalence in the CR 26%, heritability for liability 14.3% and prevalence in the subpopulation without CR 26%, the difference of estimated regression coefficient between samples with and without CR was not significant (P-value = 0.55). On the other hand, in another case with approximately >20% heritability for liability, we showed that confounding due to CR biased the estimation of exposure effects.
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Affiliation(s)
- Kyoko Shibata
- Advanced Molecular Epidemiology Research Institute (AMERI), Cohort Management Unit, Yamagata University Yamagata, Japan
| | - Atsushi Hozawa
- Division of Personalized Prevention and Epidemiology, Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University Sendai, Japan
| | - Gen Tamiya
- AMERI, Genomic Information Analysis Unit, Yamagata University Yamagata, Japan
| | - Masao Ueki
- AMERI, Genomic Information Analysis Unit, Yamagata University Yamagata, Japan
| | - Tomohiro Nakamura
- AMERI, Genomic Information Analysis Unit, Yamagata University Yamagata, Japan
| | - Hiroto Narimatsu
- AMERI, Cohort Management Unit, Yamagata University Yamagata, Japan
| | - Isao Kubota
- AMERI, Respiratory and Cardiovascular Diseases Research Center, Yamagata University Yamagata, Japan ; Department of Cardiology, Pulmonology, and Nephrology, Yamagata University Yamagata, Japan
| | - Yoshiyuki Ueno
- Department of Gastroenterology, Yamagata University Yamagata, Japan
| | - Takeo Kato
- AMERI, Metabolic and Degenerative Diseases Research Center, Yamagata University Yamagata, Japan ; Department of Neurology, Hematology, Metabolism, Endocrinology and Diabetology, Yamagata University Yamagata, Japan
| | | | - Akira Fukao
- AMERI, Genomic Information Analysis Unit, Yamagata University Yamagata, Japan ; AMERI, Cohort Management Unit, Yamagata University Yamagata, Japan
| | - Takamasa Kayama
- Graduate School of Medicine, Department of Neurosurgery, Yamagata University Yamagata, Japan
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Krueger D, Binkley N. Total body DXA: on the cusp of clinical care. J Clin Densitom 2012; 15:387-388. [PMID: 22921771 DOI: 10.1016/j.jocd.2012.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 04/18/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Diane Krueger
- Osteoporosis Clinical Research Program, University of Wisconsin - Madison, Madison, WI, USA.
| | - Neil Binkley
- Osteoporosis Clinical Research Program, University of Wisconsin - Madison, Madison, WI, USA
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Kaufman JS, Asuzu MC, Mufunda J, Forrester T, Wilks R, Luke A, Long AE, Cooper RS. Relationship between blood pressure and body mass index in lean populations. Hypertension 1997; 30:1511-6. [PMID: 9403575 DOI: 10.1161/01.hyp.30.6.1511] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Associations between body mass index (BMI) and blood pressure (BP) have been consistently observed, but remain poorly understood. One unresolved question is whether there is a linear relationship across the entire BMI range. We investigated this question among 11,235 adult men and women from seven low-BMI populations in Africa and the Caribbean. We used kernel smoothing and multivariate linear and spline regression modeling to examine gender differences in the relationship and to test for a threshold. Age-adjusted slopes of BP on BMI were uniformly higher in men than women, with pooled slope ratios of 2.00 and 2.20 for systolic and diastolic BPs, respectively. Men displayed no evidence of age modification or nonlinearity in the relationship, and the age-adjusted slope of systolic BP on BMI was 0.90 (95% confidence interval [CI], 0.76 to 1.04). Women demonstrated both age modification and nonlinearity. For both younger (<45 years) and older (45+ years) women, the optimal change point for a single threshold model was found to be 21 kg/m2. Slopes of systolic BP on BMI above this threshold were positive and significant: 0.68 (95% CI, 0.54 to 0.81) and 0.53 (95% CI, 0.29 to 0.76) for younger and older women, respectively. Slopes below the threshold were essentially zero for both groups of women, and the difference between the slopes above and below the threshold was significant for younger women (P=.019). In summary, we observed a threshold at 21 kg/m2 in the relationship between BMI and BP for women but not for men. This contributes to the effort to identify the mechanisms that underlie this relationship and how they differ by gender.
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Affiliation(s)
- J S Kaufman
- Department of Preventive Medicine and Epidemiology, Loyola University Stritch School of Medicine, Maywood, Ill, USA.
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Labarthe DR, Mueller WH, Eissa M. Blood pressure and obesity in childhood and adolescence. Epidemiologic aspects. Ann Epidemiol 1991; 1:337-45. [PMID: 1669515 DOI: 10.1016/1047-2797(91)90044-d] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Blood pressure and body mass index (BMI) are first considered independently, and then jointly, on the basis of both cross-sectional and longitudinal epidemiologic studies. The relations between these two attributes are investigated further by analysis of the "velocity curves" of age increments, from ages 6 to 24, in both blood pressure (systolic and fifth-phase diastolic) and BMI, from data from the US Health and Nutrition Examination Survey, 1971-1974. The results of both reported studies and the present exploratory analysis indicate sometimes strong but quite variable relations between blood pressure and BMI, which differ by age, gender, and the particular blood pressure measure under consideration.
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Affiliation(s)
- D R Labarthe
- Southwest Center for Prevention Research, School of Public Health, University of Texas Health Science Center at Houston 77225
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