Faculty Bibliography

INTRODUCTION: The most cost-effective diagnostic algorithm for gastroesophageal reflux disease (GERD) remains controversial. We hypothesized that prompt referral for esophageal pH monitoring is more cost-effective than prolonged empiric courses of proton-pump inhibitors (PPIs). DISCUSSION: A cost model was created based on a cohort of 100 patients with possible GERD who underwent pH monitoring. The additional costs incurred from pH monitoring were compared to the potential savings from avoiding unnecessary PPI usage in patients with a negative pH study. The costs of PPI therapy reach equivalence with pH monitoring after 6.4 to 23.7 weeks, depending on the PPI regimen. A total of 21,411 weeks of PPIs were prescribed beyond the recommended 8-week trial, of which 32 % were for patients who had a negative 24-h pH monitoring study. If the sensitivity of pH monitoring was 96 %, early referral for pH monitoring would have saved between $1,197 and $6,303 per patient over 10 years. This strategy remains cost-effective as long as the sensitivity of pH monitoring is above 35 %. Prompt referral for pH monitoring after a brief empiric PPI trial is a more cost-effective strategy than prolonged empiric PPI trials for patients with both esophageal and extraesophageal GERD symptoms.

LGR5 and BMI1 mark intestinal stem cells in crypt base columnar cells and +4 position cells, respectively, but characterization of functional markers in these cell populations is limited. ID1 maintains the stem cell potential of embryonic, neural, and long-term repopulating hematopoietic stem cells. Here, we show in both human and mouse intestine that ID1 is expressed in cycling columnar cells, +4 position cells, and transit-amplifying cells in the crypt. Lineage tracing revealed ID1+ cells to be self-renewing, multipotent stem/progenitor cells that are responsible for the long-term renewal of the intestinal epithelium. Single ID1+ cells can generate long-lived organoids resembling mature intestinal epithelium. Complete knockout of Id1 or selective deletion of Id1 in intestinal epithelium or in LGR5+ stem cells sensitizes mice to chemical-induced colon injury. These experiments identify ID1 as a marker for intestinal stem/progenitor cells and demonstrate a role for ID1 in maintaining the potential for repair in response to colonic injury.