Statins Reduce the Development of Complications in Patients With Asymptomatic Gallstone Disease: A Propensity Matched Analysis

Abstract

Introduction: In a time to event analysis, we previously demonstrated an association between statin use and a decreased frequency of gallstone-related complications in patients with asymptomatic gallstone disease. The aim of this study is to use propensity matching, a more robust form of analysis, to evaluate the efficacy of statins in reducing specific gallstone associated complications. Methods: Patients with asymptomatic gallstones diagnosed on CT or ultrasound reports between 1996 - 2016 were identified using a validated natural language algorithm. Patients with at least one completed prescription for statin were propensity matched (one-to-one with non-replacement) to patients not on statins based on 30 variables: demographic information, comorbidities, features of gallstones at the time of initial imaging, other medication use, and years to event or last follow up. Quality of propensity matching was assessed using t-test. Occurrence of gallstone complications of chronic cholecystitis (includes right upper quadrant pain), acute cholecystitis, gallstone pancreatitis, choledocholithiasis or cholangitis, gallbladder cancer or cholangiocarcinoma, and procedural interventions for these complications were compared in patients with and without statin use. Results: N=22,800 patients were propensity matched to 7,493 patients each in the statin and non-statin groups (Figure 1). T-test analysis yielded no significant differences between the groups based on any matched variables. As noted on Table 1, patients on statins had significantly reduced rates of any complication (No statins, 16.1% versus statin, 11.3%; P= versus 6.1%; P versus 2.5%; P=0.003), and gallstone pancreatitis (2.6% versus 1.8%; P=0.001). No significant differences were noted based on statin use for choledocholithiasis or cholangitis (2.5% versus 2.3%; P=0.368), gallbladder cancer or cholangiocarcinoma (0.5% versus 0.4%; P=0.377), surgery or percutaneous drainage for above indications (3.6% versus 3.1%; P=0.069).86_A Figure 1. One-to-one propensity matching was performed to match patients using statins to patients without statin use based on 30 variables. This figure shows propensity scores of the two matched groups along those excluded from the analysis.Conclusion: In this well-matched propensity analysis of a large cohort, statin use was associated with a 30% reduced incidence of subsequent cholecystitis (acute or chronic) and gallstone pancreatitis in patients diagnosed with asymptomatic cholelithiasis. Given the relative safety of statin medications, use of these medications may be considered in patients with asymptomatic gallstone disease at high risk for the development of symptomatic gallstone disease. A randomized control trial is needed to confirm these findings.86_B Figure 2. Differences in occurrence of gallstone complications in patients with and without statins.