体重指数与慢性阻塞性肺疾病及生活质量的关系

目的在2002至2004年中国7个地区（北京、上海、广东、辽宁、天津、重庆和陕西）慢性阻塞性肺疾病（COPD）现况调查的基础上，探讨体重指数（BMI）与COPD的关系。方法现况调查采用多阶段分层整群随机抽样方法，对40岁及以上的居民进行问卷调查、身高和体重的测量及肺功能检测。调查有效人数为20245名，男8705名，女11540名，以支气管扩张试验后第一秒用力呼气容积／用力肺活量（FEV1／FVC）〈70％作为COPD的诊断标准，并排除其他已知的气流受限的疾病，共筛查出1668例COPD和18577例非COPD进行BMI与COPD的关系分析。结果COPD患者的BMI[（22．7±3．5）kg／m^2]较非COPD患者[（24．1±3．4）kg／m^2]低，吸烟者BMI为[（23．6±3．4）kg／m^2]较不吸烟者[（24．2±3．5）ks／m^2]低，差异均有统计学意义（F分别为158．31、49．10，P均〈0．01），且COPD与吸烟存在对BMI的交互作用（F=6．03，P〈0．05）。COPD病情程度分级越高BMI越低（F=45．46，P〈0．01），COPD病情程度分级与BMl分级存在负相关（r=-0．08，P〈0．01）。BMI越低COPD的患病率越高（趋势x^2=102．68，P〈0．01），多因素logistic回归分析显示，与正常BMI（18．5～23．9kg／m^2）比较，1级BMI（〈18．5kg／m^2）、3级BMI（24．0～27．9kg／m^2）和4级BMI（≥28．0ks／m^2）患COPD的D尺值分别为[2．12（1．73～2．59）、0．67（0．59～0．76）、0．60（0．49～0．73），P均〈0．05]；且BMl分级与吸烟存在对COPD的交互作用（x^2=4．73，P〈O．05）。与2级BMI的COPD患者比较，1级BMI的COPD患者生活质量差（心理指数评分：55±8、57±6，F=2．96，P〈0．05；躯体指数评分：42±10、46±9，F=4．21，P〈0．01）；气促分数高（1．4±1．5、1．1±1．3，x^2=14．32，P〈0．01）。结论1级BMI与COPD关系密切，其可能是COPD患病的独立于吸烟的危险因素，而低BMI也可能是COPD病情严重程度的一个重要指标。

A study on the correlation of body mass index with chronic obstructive pulmonary disease and quality of life

OBJECTIVE: To investigate the correlation between body mass index (BMI) and chronic obstructive pulmonary disease (COPD), based on a cross-sectional COPD survey conducted in Beijing, Shanghai, Guangdong, Liaoning, Tianjin, Chongqing and Shaanxi of China between 2002-2004. METHODS: A multi-stage stratification cluster sampling strategy was used in this cross-sectional survey, and 20,245 subjects (8705 males and 11,540 females) aged 40 years or older were recruited, interviewed with a questionnaire, measured for height and weight, and tested with spirometry. 1668 subjects with post-bronchodilator FEV1/FVC less than 70% were identified as having COPD after other known causes of airflow limitation were excluded. Analysis on relationship between COPD and BMI was performed in 1668 COPD and 18 577 non-COPD subjects. RESULTS: Compared with non-COPD subjects, BMI was significantly lower in COPD patients [(22.7+/-3.5) vs (24.1+/-3.4) kg/m2, F=158.31, P<0.01]; BMI was also significantly lower in smokers than in non-smokers [(23.6+/-3.4) vs (24.2+/-3.5) kg/m2, F=49.10, P<0.01]. And an addictive interaction to BMI between COPD and smoking was observed (F=6.03, P<0.05). BMI decreased with the increase of the stage of COPD (F=45.6, P<0.01), with a negative relationship (r=-0.08, P<0.01). Lower BMI was significantly associated with increased risk of COPD (chi2=102.68, P<0.01). Compared with subjects with normal BMI (BMI=24.0-27.9 kg/m2), those with lower BMI (BMI<18.5 kg/m2) were more likely to have COPD [adjusted OR=2.12 (95% CI 1.73-2.59)], while those with higher BMI (BMI=24.0-27.9 kg/m2) and obesity (BMI>or=28.0 kg/m2) were less likely to have COPD [adjusted OR=0.67 (95% CI 0.59-0.76); and 0.60 [(95% CI 0.49-0.73), respectively]. Moreover, there was an interaction to COPD between smoking and BMI (chi2=4.73, P<0.05). Compared with COPD patients with normal BMI, the quality of life in those with lower BMI was impaired (55+/-8 vs 57+/-6 in mental scores of SF-12, F=2.96, P<0.05; 42+/-10 vs 46+/-9 in physical scores of SF-12, F=4.21, P<0.01), and their dyspnea scores were higher (1.4+/-1.5 vs 1.1+/-1.3, chi2=14.32, P<0.01). CONCLUSION: Lower BMI was strongly associated with COPD, possibly as a risk factor for COPD independent of smoking, and a potential predictor for COPD severity.