男性B型肝炎族群身體活動量和非酒精性脂肪肝病之關係:縱貫性研究

Abstract

研究背景及目的 增加身體活動量(physical activity, PA)為非酒精性脂肪肝的第一線治療，然而，目前對於預防脂肪肝的運動類型及強度，甚至是運動對於脂肪肝的長期效果，依然不甚瞭解，尤其在亞洲族群，其不同於西方國家，有相當比例的脂肪肝患者為非肥胖者。因此本研究採用縱貫性研究設計，主要研究目的包含：1) 探討有效降低脂肪肝的運動類別及強度，及2) 檢視持續運動對於脂肪肝的效果，特別著重探討身體質量指數(Body mass index, BMI)是否會影響運動和脂肪肝的關係。 研究個案及方法 本研究為縱貫性研究，樣本來源為公保健檢世代，共納入1,116位男性B型肝炎帶原且有完整運動資料者。研究起始時間為2010年，並追蹤至2018年。在每次的追蹤中，以運動問卷用收集身體活動量的資料，包含運動型態及時間，而脂肪肝則由腹部超音波診斷。總身體活動量的計算包含中等程度結合費力的活動以及肌力訓練。本研究使用廣義估計方程式估計運動對於脂肪肝的勝算比（odds ratio, OR）及95%信賴區間(confidence interval, CI)，並分析代謝因子是否為運動和脂肪肝之關係的中介因子。健康相關的生活品質則使用SF-36問卷進行測量。 研究結果 在研究起始時，研究樣本中有35.4%為肥胖者。經調整年齡、血糖及BMI，脂肪肝盛行率隨著總活動量增加而降低(P for trend= 0.0004)。就運動類型而言，肌力訓練為預防脂肪肝的最顯著的運動方式，每週≥ 2.25小時的肌力訓練者相較於未訓練者能顯著降低53% (95% CI: 0.30 - 0.73)的脂肪肝風險。縱貫分析的研究結果顯示，總身體活動量和脂肪肝呈現負相關(非常活躍 vs. 久坐，OR [95% CI] = 0.57 [0.42 - 0.77]；活躍 vs. 久坐，OR [95% CI] =0.46 [0.34 – 0.63])，且此關係在以BMI進行分層的分析中依然存在。在中介因子的分析中，使腰圍下降解釋了28.5%的總身體活動和脂肪肝的關係。就生活品質而言，不論是否有脂肪肝的樣本其HR-QoL分數都沒有差異。進一步比較有脂肪肝者和台灣常模發現，身體面向相關的分數在肥胖及有脂肪肝者較低。 結論 總身體活動量和肌力訓練與降低脂肪肝的風險呈現獨立相關性，且不論BMI所評估的肥胖程度，此關係皆存在。而腹部肥胖可能是身體活動和脂肪肝之關係的中介因子。

Background and aims Physical activity (PA) is deemed as the first line treatment for nonalcoholic fatty liver (NAFL), but the long-term effects of different types and varying intensity of PA on the development of NAFL remain unclear, especially among Asian populations, in which a significant proportion of NAFL are non-obese NAFL. Based on an established longitudinal cohort database, the overall aims of this study are 1) to examine the amounts and types of PA associated with fatty liver; 2) to determine the impacts of persistence of PA on fatty liver, with special emphasis on the assessment of the modification effect by body mass index (BMI). Material and methods In this longitudinal study, a total of 1,116 male HBV carries from the government employees’ central clinics (GECC) cohort, who had complete data of physical activity at 2010 and followed up to 2018 were included in the study. Fatty liver was diagnosed on liver ultrasound and physical activity was assessed by questionnaires at each follow-up. Total PA intensity was calculated based on the combination of moderate-to-vigorous PA and muscle-strengthening activities. Generalized estimating equation (GEE) was used to estimate odd ratios (ORs) and 95% confidence intervals (CIs) for the association between intensity and different types of PA with fatty liver. Mediation analysis was applied to evaluate the mediating roles of metabolic factors in the association between physical activity and fatty liver. Health-related quality of life (HR-QoL) was measured via SF-36 questionnaires. Results At baseline, 35.4% of subjects were obese. The prevalence of fatty liver decreased significantly with increasing total intensity of PA after adjustment for age, blood glucose, and BMI (P for trend= 0.0004). Regarding different types of PA, muscle-strengthening activity is the most significant type of PA associated with protection against fatty liver, showing a 53% (95% CI: 0.30 - 0.73) lower risk of fatty liver when comparing ≥ 2.25 hours/week of muscle-strengthening activity vs. none. In longitudinal analysis, total intensity of PA was inversely associated with fatty liver (vs. sedentary, the OR [95% CI] were 0.57 [0.42 - 0.77] and 0.46 [0.34 – 0.63], respectively, for active and very active group). This association persisted in analyses stratified by BMI. In mediation analysis, waist circumference explained 28.5% of the association between total intensity of PA and fatty liver. All HR-QoL scores showed no statistical differences between participants with and without fatty liver. When comparing HR-QoL in participants with fatty liver to the Taiwan population norm, domain scores related to physical function was lower in obese participants with fatty liver. Conclusion Total intensity of PA and muscle-strengthening activity are independently associated with lower risk of fatty liver, irrespective of BMI. The association between PA and fatty liver may be mediated by central obesity.