Are We Choosing Wisely in Lymphoma? Excessive Use of Surveillance CT Imaging in Patients with Diffuse Large B-Cell Lymphoma (DLBCL) in Long-Term Remission

Introduction

The use of surveillance CT imaging in patients with DLBCL in remission is neither effective to detect recurrence nor cost-effective. The ASH Choosing Wisely (CW) campaign, in particular, emphasizes the lack of benefit in imaging beyond 2-years of completion of therapy. We sought to describe the practice of surveillance imaging and predictors of this practice.

Methods

We used population-based health system administrative databases from Ontario, Canada. We studied a cohort of all adult patients ≥18 with diffuse large B-cell lymphoma who received R-CHOP therapy for curative intent between January 1, 2004 to June 30, 2011. Based on the CW campaign, we defined an index date of 2-years after the last dose of R-CHOP as the time-frame beyond which surveillance CT imaging would be inappropriate. The cumulative incidence of receiving CT scans within 3 years after the index date (i.e. from 2- to 5-years beyond the end of treatment) represented the primary outcome of interest (established within the Ontario Health Insurance Program database). To ensure that only surveillance scans in asymptomatic patients were captured, patients were censored 6 months prior to development of recurrent disease or a new cancer diagnosis, further chemotherapy/radiation, or if they died (censored at time of death). Predictor characteristics included baseline comorbidities (John Hopkins weighted Aggregated Diagnosis Groups (ADG) comorbidity score) and income quintile (linkage of the patient postal code to Statistics Canada Census data on average household income by postal code).

Results

The cohort consisted of 2,838 patients treated with R-CHOP during the study period. Median age at time of first R-CHOP dosing was 63 years (IQR 52-72) and the median number of cycles received was 6 (IQR 6-8). The cumulative incidence of receiving CT imaging from the index date (2-years from end of treatment) to 3-years beyond the end of treatment was 40.1% (95% CI 38.3%-41.9%). The cumulative incidence of imaging from the index date to 5-years beyond the end of treatment was 55.6 % (95% CI 53.7%-57.5%). During the follow-up period, patients ≥65 were more likely to receive imaging than those aged <65 (58.2% vs. 53.0%; p<0.01) as were those with more comorbidities (65.4% in ADG group ≥7 vs. 44.3% in ADG group 0-2; p<0.01). Income level (p=0.06) and rurality (p=0.52) did not predict for increased imaging. The cumulative incidence appeared to decrease over the study follow-up period (from 65.5% in 2006 to 47.4% in 2013; p<0.01). For the entire population, the number of CT scans completed was 0.45 per patient-year of follow-up.

Conclusion

During a time-frame in which surveillance imaging is deemed unnecessary by the CW campaign (2 to 5 years beyond therapy), the practice in a large population remains excessive (>50% cumulative incidence in scanning). Patients who are older and with more comorbidities are more likely to receive scans, and may represent target populations to ensure greater compliance with the CW campaign. This study represents a real-world baseline from which future efforts to reduce surveillance imaging can be benchmarked.