The Relationship Between Calcium Intake, Physical Activity And Perimenopausal Bone Loss

Objecive:To develope Food Frequency Questionnaire (FFQ) to estimate calcium intake in perimenopausal women in Changsha City and to provide tools for further research of the relationship between dietary calcium and postmenopause osteoporosis.Methods:3 days 24-hrs recall were used in baseline dietary survey to estimate the nutritional status among 157 recruited perimenopausal women living in Changsha urban areas, calcium-rich food, a variety of seasonal variation food, and calcium supplements were selected to compose of dietary calcium FFQ. Reproducibility validation study were conducted among those seleted volunteers with good compliance in baseline dietary survey. Reproducibility of the calcium intake FFQ was assessed four weeks later and validity was assessed by comparing the FFQ result to that 3-day 24-hrs recall. Wilcoxon signed rank test, percentage of median differences, quartile agreement rate and correlation analysis, Pearson correlation coefficient and Spearman rank correlation coefficient were used to assess the reproducibility and validity of FFQ.Results:64 calcium-rich food item were selected, take 12 calcium supplements into account, a total of 76 of food items were selected to compose of dietary calcium FFQ. Result of correlation analysis showed that the Spearman's correlation coefficient of test-retest FFQ calcium intake is 0.868 (with supplements) and 0.548 (without supplements) (P<0.001), take seasonal coefficient of 0.5 into account, the coefficient is 0.764 to 0.601 respectively(P<0.001). The Spearman's correlation coefficient of individual 3 days 24-recall and FFQ calcium intake is 0.730 (with supplements) and 0.528(without supplements) (P<0.001), take seasonal coefficient of 0.5 into account, the coefficient is 0.764 to 0.601 respectively(P<0.001).The individual actual calcium intake and FFQ estimated calcium intake showed a linear correlation, for the lowest calcium intake individual, FFQ estimated calcium intake is overestimated.Take seasonal coefficient of 0.5 into account, the adjusted quartile agreement rate (With or without supplements) of individual actual diary intake of calcium and FFQ intake is 60.42% and Kappa is 0.472(P=0.008).Compare to 3 days 24 hours recall, the validation of calcium intake FFQ(with supplements) with the seasonal adjustment factor of 0.5 is highest, and the quartile classification criteria is, low than 505.6 mg/d(quertilel), between 505.6 mg/d～652.2 mg/d (quertile2), between 652.2 mg/d～851.7mg/d(quertile 3) and great than 851.7mg/d (quertile 4). Conclusion:1. The FFQ developed to estimate calcium intake in perimenopausal women had good reproducibility and validity.2. The individual actual calcium intake and FFQ estimated calcium intake showed a linear correlation, for the lowest calcium intake individual, FFQ estimated calcium intake is overestimated.3. The FFQ has good consistency actual diary intake of calcium, with adjusted quartile agreement rate is 60.42% and Kappa is 0.472.4. The quartile classification criteria of the calcium intake FFQ is, low than 505.6 mg/d(quertilel), between 505.6 mg/d～652.2 mg/d (quertile2), between 652.2 mg/d～851.7mg/d(quertile 3) and great than 851.7mg/d(quertile 4).OBJECTIVE:To determine the relationship between dietary calcium, physical activity and their interaction with bone loss in perimenopausal women, and to provide evidence to enhance the effects and benefits of existing postmenopausal osteoporosis prevention measures.Methods:Perimenopausal women who go to Maternal and Child Health Hospital of Hunan Province perimenopausal clinic for routine physical examination were selected as subject. The bone mineral density at Femoral Neck, Ward's triangle, Trochanter, Total hip and Lumber 2-4 were measured using a LUNAR DPX-NT dual-energy X-ray absorptiometry bone densitometers produce by GE of the United States, the Daily calcium intake were estimated by the prior calcium FFQ and physical activity were estimated by WHO recommended physical activity questionnaire(IPAQ short form). The BMD were retest 10～13 months later. The subject were divide into premenopausal group and transition into menopause group (transition group) according to the situation of their menstrual frequency. Bone loss rate were calculated and compared between different calcium intake levels, different levels of physical activity and different menstrual status using the non-parametric test. Futher analysis of main effect of calcium intake, physical activity and their interaction on bone loss were analyzed by Multivariate analysis of variance, Repeated measures analysis of variance amd Mixed linear model.Result:1.189 subjects suffered from bone loss in all sites. Univariate analysis showed that menopausal status is related to bone loss rate of all sites(P<0.001). FFQ calcium intake levels is related to bone loss rate of Femoral neck, lumbar spine and total hip(P<0.001), the physical activity levels have no relationship with bone loss of all sites. 2. Results of stepwise regression, multivariate analysis of variance and repeated measures analysis showed FFQ calcium intake levels, physical activity levels and their interaction is related to bone loss rate of the menopausal transition period, but the determinants selected by each methods is not the same, Mixed linear model can isolate the random effects of subject and repeated time, and is a high-performance test.3. Mixed linear model results showed among the total variance of the femoral neck, Ward triangle, trochanter, total hip and lumbar spine bone mineral density loss, the variance attibuted to the individual variation is 61.90%,64.51%,55.0%,54.16% and 60.71% in respectively. The bone loss rate of all site in transition period women (transition group) is increase than in pre-menopausal, femoral neck, Ward triangle, trochanter, total hip, lumbar spine bone loss rate increased by 1.39%/yr,0.37%/yr, 0.58%/yr,0.59%/yr and 0.76%/yr.Calcium intake levels are closely related to the bone loss of femoral neck, Ward triangle and lumbar spine, compared to the adequate dietary calcium intake(FFQ4), low dietary calcium intake(FFQ1) leading to an additional 1.22% bone loss of the femoral neck, while leading to an additional 0.19% and 0.36% bone loss of Ward triangle and lumbar spine.Physical activity levels are closely related to the BMD of the femoral neck and related to bone loss of Ward triangle. The average BMD femoral neck in full sit-active group(PAO) is 0.0655 lower than that in high active physical activity group(PA3), while leading to an additional 0.21% bone loss of Ward triangle compared with the control.The interaction between calcium intake and physical activity level impact the bone loss of Ward triangle, trochanter and total hip. Very low calcium intake in women,Among women with very low dietary calcium intake(FFQ1), insufficient activity (PA1) leading to an additional 0.64% bone loss of the Wards triangle and an additional 0.84% bone loss of the total hip compared to the high active physical activity group(PA3). Among women with insufficient dietary calcium intake(FFQ2), insufficient activity (PA1) leading to an additional 0.79% bone loss of the Wards triangle compared to the high active physical activity group(PA3). Among women with slightly lower dietary calcium intake(FFQ3), full sit-active group(PAO) leading to an additional 1.67% bone loss of the Torchanter and an additional 1.88% bone loss rate of the totol hip.Conclusion:1 The bone loss rate of all site in transition period women (transition group) is increase than in pre-menopausal in Changsha. Variation between individuals is the main source leading to differences in bone mineral density loss.2 Calcium intake levels are closely related to the bone loss of femoral neck, Ward triangle and lumbar spine, leading to an additional 1.22%, 0.19% and 0.36% bone loss respectively, physical activity levels are closely related to bone loss of Ward triangle and leading to an additional 0.21% bone loss.The interaction between calcium intake and physical activity level impact the bone loss of Ward triangle, trochanter and total hip, the very low dietary calcium intake(FFQ1) and full sit-active (PAO) is of the greatest impact.3 Using mixed linear model to analyze re-measurement bone mineral density data, by estimate the random effect of individual and time, the parameter estimate of the main effect is more accurate and standard errors decreased. it can improving the model fit and improving the efficiency of the analysis, it is worthy be applied in the medical longitudinal data analysis.