Randomized response surface pathway design with odd response outcomes in a Latin Square designed study

Abstract

Background:Response surface pathway (RSP) design has been recently developed and described for dose-finding studies. The aim of this paper was to introduce and demonstrate additional procedures to strengthen and generalize the design and combine RSP with classical study design. Materials and methods: Nine bull calves and six heifer calves were included in an unbalanced 2 × 2 Latin Square (LSQ) designed study with large and small aperture bottle teats. The two LSQ sequences were performed with independent randomized three-level between-patient RSP design with an odd number of response classifications. The milk temperature window was 8°C-38°C with a mid temperature of 23°C. X-rays of the abdominal cavity were taken before, during, and immediately after intake of milk and recorded as "milk", "trace", or "no milk". Based on the results of the first design level, the milk temperatures for five calves in the second design level were obtained by a randomization procedure. A similar procedure was performed for seven calves in the third design level. Adjustment of the dose from one design level to the next was based on a k-adjustment factor estimated to ensure coverage of the entire predefined dose window. Results: Starting with a low number of subjects and increasing this number with increasing design levels reduces the sample size without reducing the power. The suggested randomization procedure worked as expected. No milk in Rumen was recorded and minimum milk temperature (MMT) was estimated to be ≤8°C for both teats. The odd number of response categories increases the flexibility of RSP, enabling category redefinition in hindsight from "trace" to "uncertain". After category redefinition, MMT for large bottle teat was estimated to be 14.3°C (95% confidence interval: 8.3-20.3°C), but 8°C for small. Conclusion:The suggested changes and additional procedures increase the strength and flexibility of the RSP design. Keywords: k-adjustment factor, Latin Square design, patient reduction in clinical trials, randomized response surface pathway design BackgroundDuring the first few weeks of life, milk is the primary source of nutrition for the dairy calf. Over the milk feeding period, the calf has an anatomical feature called the esophageal groove or sulcus reticuli. The groove, when activated, turns into a tube allowing the milk to pass by the reticulorumen straight into the abomasum where the milk is digested.1 Activation of the reticular groove is caused by many factors, including the smell and taste of milk, milk temperature, sucking behavior, and body posture while drinking.2 If the esophageal groove is not properly closed, milk can enter Rumen, the

Increased serum osteocalcin levels and vitamin K status by daily cheese intake

“…The study was conducted as a randomized betweenpatient, 3-level response surface pathway (RSP) designed trial with daily intake of Jarlsberg ® cheese as the intervention variable. [17][18][19] The increase in OR from baseline to three weeks with Jarlsberg ® cheese was used as the response variable. The dose-window of Jarlsberg ® cheese in the study was (20-180 g/day) with a starting mid-dose of m=100 g/day ( Table 1).…”

Randomized two dimensional between patient response surface pathway design with two interventional and one response variable in estimating minimum efficacy dose

“…The study was performed as a multicenter dose-response study of OMT in GERD patients by using a twodimensional RSP design with one year follow-up. 15,16 The study population consists of GERD patients of both genders, passed the age of 18 years with known effect of anti-reflux medication were included. 17,18 Patients with hiatus hernia ≥5 cm and patients suffering from gastric ulcer, cancer and uncontrolled bacterial, viral, fungal or parasite infection were excluded.…”

“…The study was conducted as a two-dimensional, randomized between-patient three-level RSP designed multicenter study with two interventional-and one response variable. Each of the interventional variables together with common response variables formed two independent one-dimensional randomized betweenpatient RSP studies 15 . The two interventional variable were "Number of OMT's" ranging from one to 12 and "Interval in days between each treatment" ranging from one to 10 days.…”

“…11 By starting with a low number of patients at first design level and increase this number with increased level, the sample size reduces without reduction in accuracy. 15…”

“…Such increase in number of patients from one design level to the next was solved by inclusion of randomization. 11,15 Development of the RSP-method by combining it with other study designs has also been performed to increase the strength, versatility and practical usability of the study design methodology. 15 Combining the RSP design with other traditional study designs, made RSP applicable in both controlled-and randomized controlled clinical trials.…”