ABSTRACT
BACKGROUND: Benign prostatic hyperplasia is a common disease of older males. Although the etiology remains unclear, the factors of life style and habits may have an effect on the disease.OBJECTIVE:To examine the association of cigarette smoking and body mass index with the risk of clinical benign prostatic hyperplasia.DESIGN: A hospital-based case-control study SETTINGS:Department of Epidemiology and Statistics, Public Health School,Tongji Medical College, Huazhong University of Science and Technology; Department of Preventive Medicine, Liaoning Medical College.PARTICIPANTS：Totally 343 males with benign prostatic hyperplasia of 50-82 years old (patient group),who were surgically treated between May 2004 and May 2006,were selected from the Department of Urinary Surgery of the First Affiliated Hospital and Third Affiliated Hospital of Liaoning Medical College (former Jinzhou Railway Central Hospital),Jinzhou Central Hospital and Jinzhou Second People's Hospital．Inclusive criteria：① males above 50 years old；intemational prostatic symptom score(IPSS)＞7；②Digital recta examination (DRE) after miction indicated prostate grade Ⅰ(transverse diameter＞3 cm); ③prostatic volume≥30 g;④maximum unnary flow rate＜15 mL／s；Meanwhile，361 inpatients with diseases irrelative to the risk factors of benign prostatic hyperplasia,prostatic cancer and prostatitis were selected trom the above hospitals as the control group,they were 50-82 years of age with an average of 65 years old．Informed contents were obtained from all the enrolled subjects．METHODS：All the patients and controls were interviewed using an anonymous questionnaire．All participants were asked to report whether they had smoked 20 packs of cigarettes or more in their lifetimes and,if yes,they were smokers,on the contrary they were non-smokers．Based on usual number of cigarettes reported in the questionnaire, men were categorized as 1-10，11-20，21-30 and ＞30 cigarettes per day．Based on duration of smoking,the participants were funher classified as never smoke，1-19,20-29 and ≥30 years．Body mass index(BMI)was assessed from measured body mass and body height，and che standards of BMI in adults in China was 18．5-23．9 for normal,24．0-27．9 for overweight and ≥28．0 for obesity)，then the participants were further classified as BMI＜18．4，18．5-23．9,24．0-27．9 and ≥28．0 subgroups respectively．Years of education(＜7,7-11,and≥12) and occupation(worker,peasant, Intellectual and others) were also investigated．The results of the investigation were input into computer to establish database，the odds ratios (OR) and the 95％ confidence interval(CI)in relation to the various measures were estimated using unconditional multiple logistic regression models, including number of cigarettes smoked per day，BMI,years smoked，years of education,occupation．MAIN OUTCOME MEASURES：Relationships of number of cigarettes smoked per day,years smoked．BMI,years of education and occupation with benign prostatic hyperplasia．RESULTS：Totally 343 cases in the patient group and 361 cases in the control group were involved in the analysis of results．①Patients smoked≥30 cigarettes per day had an elevated risk of benign prostatic hypertrophy as compared with the non-smokers(OR=1．32，95％ CI:0．92-2．58，P＜0．01)．②The risks of benign prostatic hypertrophy in overweight and obesity were significantly increased as compared with non-smokers(OR=1.68,95％ CI: 1．32-3．67；OR=2．35，95％CI:1．83-4．16)，③Manual worker (peasant) was negatively correlated with the risk of benign prostatic hyperplasia (χ2=6．62，P＜0．01)．CONCLUSION:Smoking 30 cigarettes per day was positively related to benign prostatic hyperplasia.For male who were both overweight(BMI 24.0-27.9)and obesity(BMI≥28.0)，smoking was significantly associated the increased risk of surgically treated benign prostatic hyperplasia.