Application of linear mixed models in the evaluation of the impact of hypo-chlorhydria in stomach on the physicochmemical characteristics of contents of stomach and upper small intentine of fasted adults

Abstract

Evaluate the impact of reduced gastric acid secretion after administration of two acid-reducing agents on the physicochemical characteristics of contents of upper gastrointestinal lumen of fasted adults using Linear Mixed Model methodology. Materials and Methods Eight healthy male adults, fasted from food for 12h, participated in a three-phase crossover study. Phase 1: No drug treatment prior to aspirations. Phase 2: Oral administration of 40mg pantoprazole at ~9am the last three days prior to aspirations and at ~7am on aspiration day. Phase 3: Oral administration of 20mg famotidine at ~7pm prior to aspirations and at ~7am on aspiration day. Samples from the contents of upper gastrointestinal lumen were aspirated for 50 min, after administration of 240ml table water. For each parameter (pH, buffer capacity, chloride ion concentration, osmolality, total protein content, free fatty acid content, total phosphatidylcholine content and cholesterol concentration), data from the three different treatments (Phase 1: Control, Phase 2: Pantoprazole and Phase 3: Famotidine), from two different locations (stomach and end of duodenum) and time points were obtained from the same subject and, therefore, were assumed to be correlated. Linear Mixed Model analysis was used to model the correlation between treatments and/or between aspiration time points using the MIXED procedure of SPSS Statistics 17.0.