painDETECT symptoms characterization by average pain severity
In 2004, the painDETECT questionnaire (PD-Q), a simple and reliable screening questionnaire of neuropathic pain, was developed in cooperation with German Research Network on Neuropathic Pain. The nine-item version comprises of seven sensory items (burning, numbness, tingling/prickling, light touching, sudden pain attacks/electric shock-type pain, cold/heat, numbness, and slight pressure), a pain course pattern item, and a pain radiation item.
The seven-item version include only the sensory items. Total scores of both versions discriminate average pain-severity levels (mild, moderate, and severe), but their ability to discriminate individual item severity has not been estimated.
The data was obtained from a study of six neuropathic pain conditions (N=624). The average pain severity was evaluated using the Brief Pain Inventory-Short Form, with severity levels described using established cut points for distinguishing mild, moderate and severe pain. The Wilcoxon rank sum test was followed by investigation to represent the probability. In this test, randomly selected subject from one average pain-severity level had a more favorable outcome on the specific painDETECT item relative to a randomly selected subject from a comparator severity level.
A probability >50% for a better outcome (less severe pain) was significantly detected for each pain symptom item. The lowest and highest probability was 56.3% (on numbness for mild vs moderate pain) and 76.4% (on cold/heat for mild vs severe pain). Pain radiation item was notable (P<0.05) and consistent with pain symptoms, plus with total scores for both painDETECT versions; only pain course item did not vary.
It was concluded that painDETECT differentiates severity like the ability to discriminate average pain also distinguishes individual pain item severity in an interpretable manner. To dictate treatment effects, pain-severity levels can serve as proxies, therefore designating probabilities for more favorable outcomes on pain symptoms.