Time spent in the lymphedema state: Area under the curve.

Abstract

252 Background: The experience of lymphedema (LE) is variable as related to the pattern of LE emergence, with characteristics related to time since diagnosis, duration of the LE episode, frequency of limb volume change (LVC) events, and overall time spent in the state defined as LE. Recognition of these characteristics, examination of trajectories, and application of the ability to quantify LE state through calculation of Area Under the Curve provide an opportunity to explore new ways to quantify LE occurrence to better examine the impact of LE on survivorship outcomes. Further, through these findings researchers and clinicians will better understand the potential variations in lymphedema experience, including patterns of emergence, duration of each episode, frequency of events, and time spent in the lymphedema state. Methods: Participants were enrolled following BC diagnosis and followed every 6 months through 60 months. The criterion of 10% LVC (LePCT) by perometry was chosen to demonstrate use of trajectories and utility of calculating Area Under the Curve (AUC). We examined times when a participant met the criterion as a means of following the trajectory of LE and quantified the proportion of (calendar) time that a participant appeared to have LE by looking at the AUC determined by the individual’s graph. As study time differed, rather than look at AUC alone, we looked at the percent of time that a participant met the LE criterion by dividing AUC by total study time. Results: Over the 60-month time-stamps of data collection points, we examined trajectories or patterns of events where participants met the LE criterion of interest. An individual may have a single LVC “spike” or may have multiple “spikes.” These cases may be acute, transient, or chronic. Further, individuals may experience the LVC early or late in the survivorship trajectory. These variations contribute to varying AUC and percent of the (calendar) time that a participant meets the LE criterion. Conclusions: These approaches provide an opportunity to further examine the association of LVC with psychosocial and functional outcomes of interest in cancer survivorship. They also provide preliminary data for exploring phenotypic differences in presentation and progression of post-breast cancer lymphedema.