Acute pain follows tissue damage (e.g., surgery) with a distinct onset and relatively brief duration that subsides as healing takes place (Vadivelu, Whitney, & Sinatra, 2009). Chronic pain persists beyond the expected period of healing, which explains why it is also called persistent pain (Pasero & Portenoy, 2011). It can occur from multiple causes (e.g., cancer, noncancer syndromes), may have a gradual or distinct onset, is often refractory to treatment, and serves no useful purpose (Vadivelu, Whitney, & Sinatra, 2009).