Background & Aims

Chronic pain presents a significant challenge for healthcare providers, with treatment outcomes that do not meet anticipated goals. We posit that treatment failures in chronic pain may, in part, stem from an incomplete understanding of the diverse patient subgroups within this population. Building upon prior research identifying three distinct clusters of chronic pain patients based on psychometric data, unrelated to specific pain diagnoses (1), our current study seeks to investigate potential differences in the efficacy of pharmacological treatment among these clusters. By elucidating the treatment response variability within each subgroup, we aim to tailor interventions more precisely to the needs of chronic pain patients, thereby enhancing treatment efficacy and patient satisfaction.

Methods

This retrospective observational cohort study comprises chronic pain patients referred to the tertiary multidisciplinary outpatient pain clinic of the University Medical Center Utrecht between 2019-2023. Clusters were defined by psychometric data from the Pain Catastrophizing Scale, Hospital Anxiety and Depression Scale and the Tampa Scale of Kinesiophobia, and differed in sociodemographic and pain characteristics.
Patients included in the study completed a patient related outcome measures (PROM) questionnaire (including the Global Perceived Effect (GPE) scale 1 to 7 (worsening pain to alleviating pain), and Numerical Rating Scale (NRS) 0 to 10 (no pain to the worst imaginable pain)). Data was collected 3, 6, 9, 12 months following the initial visit to the pain clinic. Data on analgesic drug use was extracted from electronic patient files and grouped in 11 drug family groups. Descriptive statistics were analyzed by Pearson’s-Chi-square test and Mann-Whitney test, using R4.3.3.

Results

A total of 658 (29%) chronic pain patients responded timely to the PROM questionnaire. Patients had a mean age of 58, of whom 56.4% women. The 3 most common diagnoses were mono/polyneuropathy (32.9%), arthralgia (11.2%) and abdominal pain (8.9%).
Patients in cluster 1 (n=42) with worse psychometric scores had lower educational levels and employment rates and received the most diverse multimodal drug treatment with mean of 3.1 different drugs compared to cluster 2 (n=372) with 2.5 different drugs and 2.3 in cluster 3 (n=244). Clusters are described in more detail previously (1). There was no difference in the type of pharmacological treatment received by each cluster. Cluster 1 consistently rated lowest satisfaction with pain remaining the same after treatment (mean GPE=3.9, worst NRS=8.1) compared to clusters 2 reporting a slight improvement (GPE=4.6, worst NRS=7.4), and cluster 3 (GPE=4.3, worst NRS=7.8) (1 vs. 2 p<0.01, 2 vs.3 p<0.01, 1 vs. 3 p>0.05).

Conclusions

Based on characterization of chronic pain patients with psychometric data into 3 different clusters, unrelated to diagnosis, we found variations in analgesic drug management and treatment effect reported by the patients. Although patients in cluster one were prescribed a larger number of different analgesic drug types, treatment efficacy was lower in this group. Identifying these patients early may guide patient-subgroup targeted therapy according to cluster allocation.

References

1.M Rijsdijk et al. Divergent treatment responses in chronic pain:
Identifying subgroups of patients through cluster analysis medRxiv?2024.02.23.24302234;?doi:?https://doi.org/10.1101/2024.02.23.24302234

Presenting Author

Yaara Giladi

Poster Authors

Yaara Giladi

Pain Clinic, Department of Anaesthesiology, University Medical Centre Utrecht, the Netherlands

Lead Author

Amir Giladi

Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciences

Lead Author

Lisette Vernooij

University Medical Centre Utrecht, Utrecht, the Netherlands

Lead Author

Frank J.P.M. Huygen

Pain Clinic, Department of Anaesthesiology, Erasmus Medical Centre Rotterdam, the Netherlands

Lead Author

Mienke Rijsdijk

University Medical Centre Utrecht, Utrecht, the Netherlands

Lead Author

Topics

  • Assessment and Diagnosis