Pain point system scale (PPSS): a method for postoperative pain estimation in retrospective studies

Pain rating scales are widely used for pain assessment. Nevertheless, a new tool is required for pain assessment needs in retrospective studies.

The postoperative pain episodes, during the first postoperative day, of three patient groups were analyzed. Each pain episode was assessed by a visual analog scale, numerical rating scale, verbal rating scale, and a new tool - pain point system scale (PPSS) - based on the analgesics administered. The type of analgesic was defined based on the authors' clinic protocol, patient comorbidities, pain assessment tool scores, and preadministered medications by an artificial neural network system. At each pain episode, each patient was asked to fill the three pain scales. Bartlett's test and Kaiser-Meyer-Olkin criterion were used to evaluate sample sufficiency. The proper scoring system was defined by varimax rotation. Spearman's and Pearson's coefficients assessed PPSS correlation to the known pain scales.

A total of 262 pain episodes were evaluated in 124 patients. The PPSS scored one point for each dose of paracetamol, three points for each nonsteroidal antiinflammatory drug or codeine, and seven points for each dose of opioids. The correlation between the visual analog scale and PPSS was found to be strong and linear (rho: 0.715; P < 0.001 and Pearson: 0.631; P < 0.001).

PPSS correlated well with the known pain scale and could be used safely in the evaluation of postoperative pain in retrospective studies.