A New Zealand Replication of the IPAM Clustering Model for Low Back Patients

Abstract

Objective: This study examined the releability of the three-cluster model for chronic low back pain patients found using the Integrated Psychosocial Assessment Model(IPAM). A replivation stydy using a sample of patients from a different country was completed.

Patients: Seven paitients (average age + 47.05 years.SD= 16.11) with chronic low back pain of noncancer origin participated in the study. Sixty-two of these patients were attending The Auckland New Zealand Regional Pain Service, while a further eight were attending a private practice painm service in Auckland.

Outcome Measures: Subjects were assessed on the IPAM, which measures pain intensity, disability, coping straategies, attitudes towards and beliefs about pain, depressionand illness behaviour, the Medical Examination and Deagnostic InformatinCoding System. and the Multidimensional Pain Inventory.

Results: Cluster anlysis using the k-means algorithm were performed on the IPAM data. The three-cluster solutions was preferred according to both the Variance Ratio Criterion and cluster imterpretability. Two of the three clusters correlated highly withclusters retrieved in the original study (r=0.78, r=0.71), while the third cluster showed partial resemblance (correlatonof r=0.31), Clusters were named " In Control," "Depressed and Disabled," and "High Deniers and Somatizaisers." No differences were found on the physical pathology scores between clusters. Decisionrules for cluster assignation resulted in 68% of the sample being correctly assigned.

Conclusion: Support for this cluster model from two countries suggests its value in providing a multidimensional picture of patients with chronic low back pain. The possibility of using such cluster groups for detrmining treatment type is discussed