OBJECTIVES

The concomitant use of tyrosine kinase inhibitors (TKIs) and proton pump inhibitors (PPIs) is a significant concern due to potential drug-drug interaction that reduces TKI absorption, thus potentially reducing effectiveness of TKIs. This study examined the prevalence and factors associated with concomitant use of TKIs with PPIs in older adults with cancer.

METHODS

This retrospective study used the linked SEER-Medicare data for the years 2007-2012 involving patients with lung, renal cell, leukemia, liver and pancreatic cancer with Medicare part D claims. The study sample (12,538 patients) included those using TKIs, namely erlotinib, sunitinib, imatinib, sorafenib, nilotinib, dasatinib and lapatinib. Descriptive analyses were used to examine the concomitant use of TKI and PPI defined as at least 30 days of overlap of TKI and PPI claim within first 90 days of starting a TKI. Multivariable logistic regression analysis examined various demographic factors, comorbidities, and medications associated with concomitant use of TKI and PPI.

RESULTS

The prevalence of concomitant use of TKI and PPI in the linked SEER-Medicare data was 22.7% (N=2,843/12,538). The factors significantly associated with increased likelihood of concomitant use of TKI and PPI were polypharmacy (use of 5 or more medicines) (aOR=3.92, 95% CI:2.64-5.83), prior PPI use (aOR=3.84, 95% CI:3.34-4.40), non-steroidal anti-inflammatory use (aOR=1.44, 95% CI:1.30-1.60), diagnosis of gastroesophageal reflux disease and gastric ulcers (aOR=2.76, 95% CI:2.51-3.05; aOR=1.46, 95% CI:1.19-1.80 respectively), prior chemotherapy (aOR=1.38, 95% CI:1.15-1.66) and higher Charlson’s comorbidity score (aOR for 2 =1.17, 95% CI: 1.00-1.35; aOR for 3 and higher =1.37, 95% CI: 1.20-1.56 respectively).

CONCLUSIONS

Nearly one in four older cancer patients taking TKIs used PPIs concomitantly, and several potentially modifiable factors were associated with this concomitant use. Concerted drug reconciliation efforts are needed to evaluate PPI use when TKIs or oral chemotherapeutic agents are initiated.