Pilot Study Of Pregabalin And Prediction Of Treatment Response In Patients With Postherpetic Neuralgia

NPSI: participant rated questionnaire to evaluate different symptoms of neuropathic pain (dimensions: burning [superficial] spontaneous pain, pressing [deep] spontaneous pain, paroxysmal pain, evoked pain, and paresthesia/dyesthesia [P/D]). Includes 10 descriptors quantified on a 0 (no symptoms) to 10 (worst symptoms imaginable) and 2 temporal items assessing duration of spontaneous ongoing and paroxysmal pain. Questionnaire generates a score in each of the relevant dimensions and a total score of 0-100. Higher score indicates a greater intensity of pain.

To explore whether sensory symptom cluster analysis is useful for predicting treatment response in paticipants with PHN, identification of the phenotype was initially required of all participants using three different approaches (with or without the baseline PHQ-8, GAD-7 Pain Related Sleep Interference Score Scale, PCS): 1. PainDETECT at baseline, 2. PainPREDICT at baseline, 3. NPSI at baseline. Then for each of the above phenotypes the distribution of the pregabalin responders (using 30% and 50%) were to be compared.

PGIC: participant rated instrument to measure participant's change in overall status on a 7-point scale; range from 1 (very much improved) to 7 (very much worse).

The daily pain diary consists of an 11-point numeric scale ranging from 0 ("no pain") to 10 ("worst possible pain"). Participants describe their pain during the previous 24 hours by choosing the appropriate number between 0 and 10. Self-assessment is performed daily at bedtime on a telephone via interactive voice response system (IVRS). The endpoint mean pain score is defined as the mean of the last 7 daily diary pain ratings while taking study medication in the open-label phase. Daily pain IVRS diaries were completed daily at bedtime from Visit 1 (Screening) through Visit 7/Early Termination. Participants were asked to complete their first IVRS daily at bedtime on the morning after Visit 1.

To explore whether sensory symptom cluster analysis is useful for predicting treatment response in paticipants with PHN, identification of the phenotype was initially required of all participants using three different approaches (with or without the baseline PHQ-8, GAD-7 Pain Related Sleep Interference Score Scale, PCS): 1. PainDETECT at baseline, 2. PainPREDICT at baseline, 3. NPSI at baseline.

The PHQ-8 is a self-administered version of the PRIME-MD diagnostic instrument for common mental disorders. The PHQ-9 is the depression module, which scores each of the 9 DSM-IV criteria as 0 (not at all) to 3 (nearly every day). The PHQ-8 is a validated subset of the PHQ-9, which comprises the first 8 items of the measure. The GAD-7 is a 7-item questionnaire that assesses anxiety. Participants respond as to how each item applies to them on a 4 point response scale. The higher the score, the more severe the anxiety.

The Brief Pain Inventory-Short Form (BPI-sf) consists of 5 questions. Questions 1, 2, 3, and 4 measure pain on an 11-point scale from 0 (no pain) to 10 (worst pain possible).

The PCS is a 13-item self report instrument and requires a Grade 6 reading level and has been translated into 12 languages. It instructs participants to reflect on past experience of pain and indicate their experience using a 5-point scale. The PCS was designed for research on catastrophizing and pain experience. Catastrophizing is associated with heightened pain and is "an exaggerated negative mental set brought to bear during actual or anticipated painful experience." It is a multidimensional construct compromising elements of rumination, magnification, and helplessness and its factor structure has been replicated. It has a total score and three subscale scores (score range of 0-52).

The numeric rating scale for pain (NRS-Pain) consists of an 11-point NRS ranging from 0 (no pain) to 10 (worst possible pain). A rating of 1-3 is considered mild pain; 4-6, moderate pain; and 7-10, severe pain.

The Short-Form 12 Health Survey (SF-12v2) is a self-administered, validated questionnaire that measures each of the following 8 health aspects: Physical functioning, role limitations due to physical problems, social functioning, bodily pain, mental health, role limitations due to emotional problems, vitality, and general health perception over the past week. Higher scores indicate a better health-related quality of life.

The pain-related sleep interference item rating scale is scored on an 11-point numeric rating scale (NRS-Sleep). It is self-administered by the participant in order to rate how pain has interfered with their sleep during the past 24 hours, ranging from 0 (pain does not interfere with sleep) to 10 (completely interferes (unable to sleep due to pain). Participants are to describe how their pain has interfered with their sleep during the past 24 hours by choosing the appropriate number on the numeric rating scale.