Approaches to sample size calculation for clinical trials in rare diseases.

We discuss 3 alternative approaches to sample size calculation: traditional sample size calculation based on power to show a statistically significant effect, sample size calculation based on assurance, and sample size based on a decision-theoretic approach. These approaches are compared head-to-head for clinical trial situations in rare diseases. Specifically, we consider 3 case studies of rare diseases (Lyell disease, adult-onset Still disease, and cystic fibrosis) with the aim to plan the sample size for an upcoming clinical trial. We outline in detail the reasonable choice of parameters for these approaches for each of the 3 case studies and calculate sample sizes. We stress that the influence of the input parameters needs to be investigated in all approaches and recommend investigating different sample size approaches before deciding finally on the trial size. Highly influencing for the sample size are choice of treatment effect parameter in all approaches and the parameter for the additional cost of the new treatment in the decision-theoretic approach. These should therefore be discussed extensively.

Recombinant Bile Salt-Stimulated Lipase in Preterm Infant Feeding: A Randomized Phase 3 Study.

INTRODUCTION: Feeding strategies are critical for healthy growth in preterm infants. Bile salt-stimulated lipase (BSSL), present in human milk, is important for fat digestion and absorption but is inactivated during pasteurization and absent in formula. This study evaluated if recombinant human BSSL (rhBSSL) improves growth in preterm infants when added to formula or pasteurized breast milk. PATIENTS AND METHODS: LAIF (Lipase Added to Infant Feeding) was a randomized, double-blind, placebo-controlled phase 3 study in infants born before 32 weeks of gestation. The primary efficacy variable was growth velocity (g/kg/day) during 4 weeks intervention. Follow-up visits were at 3 and 12 months. The study was performed at 54 centers in 10 European countries. RESULTS: In total 415 patients were randomized (rhBSSL n = 207, placebo n = 208), 410 patients were analyzed (rhBSSL n = 206, placebo n = 204) and 365 patients were followed until 12 months. Overall, there was no significantly improved growth velocity during rhBSSL treatment compared to placebo (16.77 vs. 16.56 g/kg/day, estimated difference 0.21 g/kg/day, 95% CI [-0.40; 0.83]), nor were secondary endpoints met. However, in a predefined subgroup, small for gestational age infants, there was a significant effect on growth in favor of rhBSSL during treatment. The incidence of adverse events was higher in the rhBSSL group during treatment. CONCLUSIONS: Although this study did not meet its primary endpoint, except in a subgroup of infants small for gestational age, and there was an imbalance in short-term safety, these data provide insights in nutrition, growth and development in preterm infants. TRIAL REGISTRATION: ClinicalTrials.gov NCT01413581.

rhBSSL improves growth and LCPUFA absorption in preterm infants fed formula or pasteurized breast milk.

OBJECTIVES: Preterm infants often experience suboptimal growth, which can affect organ development. The aim of this study was to improve growth by treatment with bile salt-stimulated lipase (BSSL), naturally present in breast milk, but lost after pasteurization, and absent in formula. METHODS: Two clinical trials were performed with a predefined analysis of combined data to investigate the effects of recombinant human BSSL (rhBSSL) treatment on growth velocity and fat absorption in preterm infants. The studies were randomized and double-blinded comparing 7-day treatment with rhBSSL and placebo, administered in pasteurized breast milk or formula, using a crossover design. RESULTS: Sixty-three infants were evaluated for safety. At randomization, the mean (standard deviation) weight was 1467 (193) g and mean postmenstrual age was 32.6 (0.5) weeks. Sixty and 46 infants were evaluated for growth velocity and fat absorption, respectively. rhBSSL treatment significantly improved mean growth velocity by 2.93 g · kg · day (P<0.001) compared with placebo (mean 16.86 vs 13.93 g · kg · day) and significantly decreased the risk of suboptimal growth (<15 g · kg · day) (30% vs 52%, P=0.004). rhBSSL significantly increased absorption of the long-chain polyunsaturated fatty acids, docosahexaenoic acid, and arachidonic acid by 5.76% (P=0.013) and 8.55% (P=0.001), respectively, but had no significant effect on total fat absorption. The adverse-event profile was similar to placebo. CONCLUSIONS: In preterm infants fed pasteurized breast milk or formula, 1 week of treatment with rhBSSL was well tolerated and significantly improved growth and long-chain polyunsaturated fatty acid absorption compared to placebo. This publication presents the first data regarding the use of rhBSSL in preterms and the results have led to further clinical studies.

A double blind, randomized, placebo-controlled trial of quetiapine as an add-on therapy to lithium or divalproex for the treatment of bipolar mania.

The aim of this study was to evaluate the efficacy and tolerability of quetiapine combined with lithium or divalproex in the treatment of bipolar mania. Patients were randomized to 6 weeks of quetiapine (up to 800 mg/day) and lithium/divalproex (Li/DVP) (target trough serum concentrations of 0.7-1.0 mEq/L and 50-100 microg/mL, respectively) or placebo and lithium/divalproex. Quetiapine+lithium/divalproex treatment (n=104) showed a 2.0-point greater improvement on the primary outcome (change from baseline in Young Mania Rating Scale total score at day 21) compared with placebo+lithium/divalproex (n=96), and a 2.8-point greater difference by day 42, but the differences between groups were not statistically significant. Other efficacy measures, however, did show a statistically significant advantage in favor of quetiapine+lithium/divalproex over lithium/divalproex monotherapy at day 42. Improvement of mean Young Mania Rating Scale scores with quetiapine+lithium/divalproex was numerically but not statistically significantly greater than lithium/divalproex monotherapy in the treatment of bipolar mania. Potential reasons for the failure of quetiapine+lithium/divalproex to differentiate from placebo+lithium/divalproex treatment on the primary outcome measure and the implications of this for the treatment of mania and future studies are discussed. Overall, the combination of quetiapine with lithium or divalproex was well tolerated.

Rates of remission/euthymia with quetiapine in combination with lithium/divalproex for the treatment of acute mania.

OBJECTIVE: The aim of this analysis was to compare the rates of remission/euthymia in patients with bipolar mania receiving quetiapine in combination with lithium/divalproex (QTP+Li/DVP) versus placebo (PBO) in combination with Li/DVP (PBO+Li/DVP). METHODS: A pooled analysis of two (one 3-week and one 6-week) double-blind studies of a total of 370 patients hospitalized with bipolar I mania who received quetiapine (up to 800 mg/day) in combination with Li (mean serum concentration 0.76 mEq/L) or DVP (mean serum concentration 69.5 microg/mL) was performed. For both studies, data were analyzed at Day 21. In addition, for the 6-week study, data were analyzed at Day 42. Five different criteria for remission/euthymia were used: (i) Young Mania Rating Scale (YMRS) score < or = 12; (ii) YMRS score < or = 12 plus a Montgomery-Asberg Depression Rating Scale (MADRS) score < or = 10; (iii) YMRS score < or = 12+MADRS score < or = 8; (iv) YMRS score < or = 8; and (v) YMRS score < or = 8 plus a score < or = 2 for the YMRS core items of Irritability, Speech, Content, and Disruptive/Aggressive Behavior. RESULTS: In the pooled analysis, Day 21 remission rates (YMRS < or = 12) were significantly higher in patients treated with QTP+Li/DVP compared with those who received PBO+Li/DVP (48.7% versus 33.0%, p=0.003). Rates of remission/euthymia (YMRS < or = 12+MADRS < or = 10) were similarly improved with QTP+Li/DVP compared with Li/DVP alone (43.2% versus 26.5%, p=0.001). Using the most stringent criteria (YMRS < or = 12+MADRS < or = 8), rates of remission/euthymia were again significantly higher with QTP+Li/DVP than with Li/DVP alone (38.4% versus 25.9%, p=0.014). More patients treated with quetiapine met the stringent criterion of YMRS < or = 8 (31.9% versus 24.3%; p=NS). A trend in favor of quetiapine was also observed for the more stringent criterion of YMRS < or = 8 plus core items < or = 2 (28.1% versus 23.2%; p=NS). For the 6-week study, at Day 42, YMRS was < or = 12 in 68.3% of patients treated with QTP+Li/DVP compared with 57.3% of those who received PBO+Li/DVP (p=NS). Respective rates based on the remission criterion of YMRS < or = 8 were 36.5% and 32.3% (p=NS), and with YMRS < or = 8 and core items < or = 2 were 53.8% and 45.8% (p=NS). However, a significant difference was observed between patients treated with QTP+Li/DVP versus those treated with PBO+Li/DVP using criteria of YMRS < or = 12+MADRS < or = 10 (63.5% versus 49.0%, p<0.05) or YMRS < or = 12+MADRS < or = 8 (61.5% versus 46.9%, p<0.05). CONCLUSIONS: At Days 21 and 42, quetiapine combined with Li/DVP compared to Li/DVP monotherapy yielded significant, sustained improvements in the rate of clinical remission/euthymia in patients with bipolar mania. Longer-term studies are warranted to assess whether quetiapine combined with other mood stabilizing medications can yield even longer-term resolution of symptoms of acute mania while concurrently preventing emergence of depressive symptoms.

Quetiapine in the treatment of acute mania: target dose for efficacious treatment.

OBJECTIVE: To analyze the available evidence from randomized clinical trials regarding the effective dose range and optimal dose of quetiapine when treating bipolar I disorder patients with acute mania. METHODS: Patients with acute mania were treated with quetiapine as monotherapy (for 12 weeks) or in combination with lithium (mean serum concentration 0.76 mEq/L) or divalproex (mean serum concentration 69.5 microg/mL) (Li/DVP) (for 3-6 weeks) in four double-blind, placebo-controlled studies according to a predetermined dosing schedule. Guidance for the dosing of quetiapine involved increasing the first day's dose (100 mg/day) by 100 mg on a daily basis until Day 4 (400 mg/day), then adjusting the dose up to 600 mg/day at Day 5, and up to 800 mg/day thereafter. Pooled data from the two monotherapy studies and the two combination therapy studies have been used to evaluate the effective quetiapine dose range. As the dose was flexible, effective dose was estimated by the mean last-week dose among responders. The mean last-week dose was defined as the median dose during the 7 days before the last available Young Mania Rating Scale (YMRS) assessment. Patients who achieved a > or = 50% decrease in the YMRS total score from baseline to end of treatment with quetiapine were considered responders. Tolerability was assessed from direct patient reports. RESULTS: According to randomized clinical trials, administration of quetiapine compared with placebo achieved a statistically significant improvement in change from baseline YMRS score within the first week and onward, as monotherapy or in combination with Li/DVP. The average quetiapine dose (+/-SD) in responders during the last week of treatment was 575 (+/-175) at Day 21 and 598 (+/-198) mg/day at Day 84 for monotherapy, and 584+/-208 mg/day at Day 21 for combination therapy, with most responders receiving doses within the range of 400-800 mg/day. Dose escalation was rapid, with 92% of patients treated with monotherapy and 80% of patients treated with combination therapy reaching doses of 400 mg/day by Day 4, in accordance with protocol-defined dosing guidance. This dose administration schedule was generally well tolerated. CONCLUSIONS: The mean last-week median dose among responders suggests that 600 mg/day of quetiapine is an effective target dose in acute mania.

A randomized, double-blind, placebo-controlled efficacy and safety study of quetiapine or lithium as monotherapy for mania in bipolar disorder.

OBJECTIVE: To evaluate the efficacy and tolerability of quetiapine monotherapy versus placebo for the treatment of mania associated with bipolar disorder. METHOD: In an international, multicenter, double-blind, parallel-group, 12-week study, patients with a DSM-IV diagnosis of bipolar I disorder (manic episode) were randomly assigned to treatment with quetiapine (flexibly dosed up to 800 mg/day), placebo, or lithium. The primary efficacy measure was change from baseline in Young Mania Rating Scale (YMRS) score at day 21. Data were gathered from April 2001 to May 2002. RESULTS: More patients in the quetiapine (72/107) and lithium (67/98) groups completed the study compared with the placebo group (35/97). Improvement (reduction) in YMRS score was significantly greater for quetiapine than placebo at day 7 (-8.03 vs. -4.89; p < .01), and the difference between groups continued to increase over time to day 21 (-14.6 vs. -6.7; p < .001) and to endpoint at day 84 (-20.3 vs. -9.0; p < .001). Significantly more quetiapine patients compared with placebo patients fulfilled YMRS response criteria at day 21 (53.3% vs. 27.4%; p < .001) and at day 84 (72.0% vs. 41.1%; p < .001). Quetiapine was also superior to placebo in efficacy at day 21 and day 84 by all secondary measures. Lithium-treated patients improved significantly compared with placebo patients and similarly to quetiapine-treated patients on the primary efficacy measure. The most common adverse events for quetiapine were dry mouth, somnolence, and weight gain, while lithium was associated with tremor and insomnia. The quetiapine and placebo groups had similar, low levels of extrapyramidal symptom-related adverse events. CONCLUSIONS: Quetiapine demonstrated superior efficacy to placebo in patients with bipolar mania and was well tolerated.