The treatment of breakthrough pain (BTP) with supplemental (“rescue”) opioids in patients with chronic cancer pain is well supported; use of this approach in patients with chronic noncancer pain is increasing. Traditionally, a dose of a supplemental opioid for BTP is calculated as a percentage of the patient's total, daily around-the-clock (ATC) opioid dosage used to control persistent pain. Accumulating evidence suggests that, in contrast to traditional practice, individual titration may be necessary to identify the most effective dose of an opioid for BTP. This analysis evaluated data from two randomized, placebo-controlled studies of fentanyl buccal tablet (FBT), a rapid-onset fentanyl formulation—one in persistent low back pain, one in persistent neuropathic pain. The objective was to assess correlations between doses of FBT and doses of patients' ATC opioids and prior supplemental opioids, using Spearman rank correlation. In both studies, eligible patients first entered an open-label phase in which FBT (100-800 µg tablet) was individually titrated to a dose effective for BTP. Patients identifying an effective dose entered a double-blind treatment phase. Combined data from the dose-titration phases were analyzed. Of 206 patients, 164 (80%) identified an effective FBT dose. ATC opioids included oxycodone (33% of patients), fentanyl (25%), morphine (23%), methadone (14%), and hydrocodone (9%). Prior supplemental opioids included oxycodone (42%), hydrocodone (33%), fentanyl (15%), morphine (6%), and hydromorphone (5%). No clinically meaningful correlations were found between effective doses of FBT and patients' ATC opioid doses (r=0.3066; n=120), ATC transdermal fentanyl doses (r=0.3578; n=36), or prior supplemental opioid doses (r=0.2774; n=156). It can be concluded that there were no correlations of predictive value. Therefore, titration—beginning from the lowest dose (100 µg)—should be individualized to identify the most effective dose of FBT for BTP.