Influence of smoking, coffee, and tea consumption on bladder pain syndrome in female twins

Objectives: To assess the influence of smoking, coffee and tea consumption on the risk for bladder pain syndrome (BPS) using the O'Leary Interstitial Cystitis Symptom Index (ICSI). Methods: In 2005, all twins born between 1959 and 1985 in Sweden (n = 42,852) were invited to participate in a web-based survey to screen for complex diseases, including BPS. Analyses were limited to female twins with information regarding bladder pain symptoms (n = 9349). Women with an ICSI score <6 with required nocturia and bladder pain were defined as having BPS symptoms. Logistic regression was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs). Environmental and genetic influences were assessed in co-twin control analysis. Results: Tea consumption was associated with an increased risk for BPS (OR 1.26, 95% CI 1.02-1.55 for low tea consumption; OR 1.74, 95% CI 1.24-2.44 for high tea consumption). Coffee consumption was not a risk factor for BPS (OR 1.1, 95% CI .84-1.45). Former and current smoking was associated with a higher risk of BPS (OR 1.5, 95% CI 1.18-1.89; and OR 1.49, 95% CI 1.16-1.92, respectively), but results from co-twin control analysis suggested that the association between smoking and BPS was confounded by familial factors. Conclusions: Tea and smoking are environmental risk factors for BPS, which are amenable to intervention. The effects of smoking on the risk for BPS may, however, be confounded by familial factors. © 2011 Elsevier Inc.