A Multi-Center Cohort Study on Characteristics of Pain, Its Impact and Pharmacotherapeutic Management in Patients with ALS

Abstract

Background: Although pain is common in amyotrophic lateral sclerosis (ALS) and an effectively treatable symptom, it is widely under-recognized and undertreated. This study investigates epidemiological and clinical characteristics of pain, its impact and pharmacological treatment in ALS patients. In addition, opportunities for further optimization of pain therapy need to be identified.

Methods: Patients from three German ALS outpatient clinics were asked to complete the Brief Pain Inventory and the ALS Functional Rating Scale-Extension and to participate in semi-structured telephone interviews.

Results: Of the 150 study participants, 84 patients reported pain. Pain occurred across all disease stages, predominantly in the neck, back and lower extremities. It was described with a broad spectrum of pain descriptors and mostly interfered with activity-related functions. Of the 84 pain patients, 53.8% reported an average pain intensity ≥4 on the numerical rating scale (NRS), indicating pain of at least moderate intensity, and 64.3% used pain medication. Irrespective of the medication type, 20.4% of them had no sufficient pain relief. Thirteen out of 30 patients without pain medication reported an average NRS value ≥4. Eleven of them-mainly in the context of high pain interference with daily functions-were supposed to benefit from adequate pain therapy. However, many patients had relevant concerns and misconceptions about pain therapy.

Conclusion: Given the frequency, extent and multi-faceted impact of pain, it is necessary to systematically assess pain throughout the disease course. Potentials to optimize pain therapy were seen in the subset of patients with insufficient pain relief despite medication and in those patients without pain medication but high pain interference. However, there is a need to respond to patients' barriers to pain therapy.

Keywords: amyotrophic lateral sclerosis; daily functions; motor neuron disease; pain; pharmacotherapy.

Figure 1

Pain intensity according to the Brief Pain Inventory (BPI) for the average pain in the past week (light gray bars) and for the most severe pain in the past week (dark gray bars). The number of respondents is given as percentages. The pain intensity is scaled from 0 (=no pain) to 10 (=strongest pain imaginable) points on the numerical rating scale. The increasing levels of the average pain intensity are highlighted in shades of red from lighter to darker.

Figure 2

Representation of pain locations on front and back body diagrams indicating percentage frequency distributions for the patients with pain.

Figure 3

Descriptors of the pain sensations listed in the BPI with means (M) and standard deviations (SD) as well as the percentage of the respondents reporting the respective type of pain. The boxes of each stacked bar graph illustrate the response categories of the respective item from 0 = no pain to 3 = extreme pain. The height of the boxes shows the percentage of respondents who chose the respective response category. The items for pain descriptions are arranged within the respective pain components in descending order of frequency.

Figure 4

Daily functions impaired by pain, indicating the mean values on a scale from 0 (=does not interfere) to 10 (=completely interferes). The items are arranged within the respective BPI subdimensions of pain interference in descending order of the mean values. BPI = Brief Pain Inventory; REM = affective subdimension of the BPI; WAW = activity subdimension of the BPI.

Figure 5

Characteristics of the 13 patients who did not receive any pain medication and who reported an average NRS value ≥4. The figure summarizes the demographic, clinical and pain-related data as well as the patient-reported barriers to pain medication with the patients being arranged according to the BPI pain interference total score (BPI-PITS) in ascending order. Pain interference scores ≥7 were categorized as high and are highlighted in dark red. For visualization of the level of pain interference referring to the scores between 0 and 6, an additional color scale from white to shades of yellow and orange was used. The findings highlighted by dark red boxes prompted us to assume that the respective patients may benefit from adequate pain therapy.