Patient expectation of the partial response and response shift in pain score

The aim of this study was to define the minimum reduction in pain level that patients would expect and to examine whether response shift exists in the treatment of bone metastases with palliative radiation therapy (RT).

Patients with bone metastases were asked to quantify the minimal level of pain reduction by 2 months that they considered would justify the palliative RT based on their current pain (on a scale of 0-10 and a 4-point scale of none, mild, moderate, or severe). At the 2-month follow-up, they were asked the conventional "post-test" question, ie, what is their level of pain now? In addition, they were asked to retrospectively reevaluate their baseline "pretest" level of pain, which is referred to as a "then-test," ie, how would they now rate their level of pain before RT?

Two hundred seventeen patients were enrolled. The median minimum pain reduction they would expect from the radiation treatment at the time of consultation was 4. Patients expected a reduction of 50%-70% in their baseline pain after radiation treatment. At 2 months, 114 patients participated in the response shift study. Only 31 patients reported no change between the pretest and then-test pain scores. The other 83 patients (73%) demonstrated a response shift but in opposing directions.

Patients with bone metastases expected a 50%-70% reduction in pain score from baseline with the palliative RT. This might become the definition of partial response in future trials. Response shift was observed in this group of patients but in opposing directions and without affecting the overall outcome.