Doug Brunk/MDedge News
Dr. Gareth Morris-Stiff
“Most patients with asymptomatic gallstones never develop symptoms and probably don’t need surgical intervention,” lead study author Gareth Morris-Stiff, MD, PhD, said at the annual Digestive Disease Week.
Dr. Morris-Stiff, of the department of general surgery at Cleveland Clinic, said that, while previous studies have evaluated the time to development of gallstone-related complications following identification of asymptomatic gallstones, factors associated with the need for surgical intervention in this population have not been documented. The aims of the current study were to perform a big data analysis to evaluate risk factors associated with intervention in asymptomatic gallstones and to develop a risk stratification tool to aid in patient consultations by predicting individuals likely to need future intervention for their gallstones.
The researchers included Cleveland Clinic patients with CT/US reports containing “cholelithiasis” or “gallstones” between January 1996 and December 2016. Patients were excluded if they had a concurrent or prior event, had an event within 2 months, or lacked follow-up. Data collection included demographic characteristics, comorbid conditions or surgeries, imaging features, and medication use.
Dr. Morris-Stiff and his colleagues constructed Kaplan-Meier curves to analyze time to intervention and calculated cumulative incidence ratios. They used automated forward stepwise competing risk regression to create their model and receiver operating characteristics curves to analyze it.
Of the 49,414 patients identified with asymptomatic gallstones, 22,257 met criteria for analysis. Slightly more than half (51%) were female, their mean age was 61 years, 80% were white, 16% were black, and the rest were from other racial and ethnic groups. The median follow-up was 4.5 years, and the median follow-up of patients undergoing intervention was 3.9 years. This translated to 112,111 total years of observation.
The researchers found that the cumulative incidence of intervention at 15 years was 25% and it increased linearly from the time of initial diagnosis of asymptomatic gallstones. A total of 1,762 patients (7.9%) underwent a surgical procedure, most often cholecystectomy (5.7%). Three factors were associated with a reduced risk for surgical intervention: increasing age (hazard ratio, 0.94; P less than 0.001), male gender (HR, 0.78; P less than 0.001), and statin use (HR, 0.67; P less than 0.001).
Patient variables associated with an increased need for surgical intervention included obesity (HR, 1.44; P less than 0.001) and having a hemolytic disorder (HR, 2.42; P less than 0.001). Gallstone-specific characteristics that increased the need for surgical intervention included a stone size of greater than 9 mm (HR, 1.56; P less than 0.001), the presence of sludge (HR, 1.46; P less than 0.001), the presence of a polyp (HR, 1.68; P less than 0.001), and having multiple stones (HR, 1.69; P less than 0.001).
The analysis enabled Dr. Morris-Stiff and colleagues to generate a Web-based risk score to reliably identify these patients and provide prognostic information for counseling. An app for smartphones based on the score is being developed. The researchers reported having no financial disclosures.