Combination of Equisetum Arvense and Palmitoylethanolamide (PEA) for the Management of Patients With Chronic Pain in a Before-after Study

The primary endpoint was the reduction of perceived pain, which was measured using the NPRS at T0, T1, T2, T3. The NPRS (or NRS scale) is a one-dimensional 11-point scale that assesses the intensity of pain in adults, including chronic pain conditions due to rheumatic diseases]. The scale is composed of a horizontal line, with an interval ranging from 0 to 10, corresponding to "no pain" and "worst imaginable pain", respectively. The NPRS scale can be easily administered both verbally (for example, also by telephone) and graphically.

The Verbal Rating Scale (VRS) is a pain scale consisting of a list of descriptors that identify the degree of pain intensity. Generally, the scale ranges from "no pain" to "severe pain" or "very intense pain," passing through a series of intermediate adjectives that should gradually capture the nuances of intensity of the painful experience, such as "mild," "moderate," and "severe."

The measurement of patient perception versus drug treatment, which will be measured with the GPE, a scale that assesses patient perception using a 7-point Likert scale. This is a subjective assessment in which the patient indicates how much they feel improved or worsened compared to before treatment (1: Very much worse; 2: Moderately worsened; 3: Slightly improved; 4: No change; 5: Slightly improved; 6: Moderately improved; 7: Much improved). This scale is widely used in clinical trials and clinical practice to assess the effectiveness of therapeutic interventions, particularly in musculoskeletal and rehabilitation settings.

The quantification and description of perceived pain will be assessed using the SF-MPQ. It is a self-assessment questionnaire that al-lows you to have an accurate description of the quality and intensity of the pain that the subject is experiencing. There are 78 items di-vided into 20 subgroups that refer to 4 main categories: the sensory class, the affective class, the valuative class and the miscellaneous class. The SF-MPQ also includes the Pain Intensity Index (PPI) of the standard MPQ and a visual analogue scale (VAS).

Measuring quality of life, described with the EURO-QoL-5D-5L or EQ-5D-5L. The instrument consists of: a 5-dimensional descriptive system (mobility, self-care ability, habitual activities, pain/discomfort, and anxiety/depression), each of which involves a three-point rating scale (no problem=1 point; some problem=2 points; persistent problem=3 points); and a VAS that requires the subject to answer the question, "How healthy do you feel today?" A score of 0 corresponds to the worst health status ever, while 100 equals the best perceived health level. It is possible to combine the scores of the two sections and determine an overall score