Objective: (i) To analyze general practitioners' diagnosis of somatisation disorder (P75) using the International Classification of Primary Care (ICPC)-2-E in routine general practice. (ii) To validate the distinctiveness of the ICD-10 to ICPC-2 conversion rule which maps ICD-10 dissociative/conversion disorder (F44) as well as half of the somatoform categories (F45.0-2) to P75 and codes the other half of these disorders (F45.3-9), including autonomic organ dysfunctions and pain syndromes, as symptom diagnoses plus a psychosocial code in a multiaxial manner.
Methods: Cross-sectional analysis of routine data from a German research database comprising the electronic patient records of 32 general practitioners from 22 practices. For each P75 patient, control subjects matched for age, gender, and practice were selected from the 2007 yearly contact group (YCG) without a P75 diagnosis using a propensity-score algorithm that resulted in eight controls per P75 patient.
Results: Of the 49,423 patients in the YCG, P75 was diagnosed in 0.6% (302) and F45.3-9 in 1.8% (883) of cases; overall, somatisation syndromes were diagnosed in 2.4% of patients. The P75 coding pattern coincided with typical characteristics of severe, persistent medically unexplained symptoms (MUS). F45.3-9 was found to indicate moderate MUS that otherwise showed little clinical difference from P75. Pain syndromes exhibited an unspecific coding pattern. Mild and moderate MUS were predominantly recorded as symptom diagnoses. Psychosocial codes were rarely documented.
Conclusions: ICPC-2 P75 was mainly diagnosed in cases of severe MUS. Multiaxial coding appears to be too complicated for routine primary care. Instead of splitting P75 and F45.3-9 diagnoses, it is proposed that the whole MUS spectrum should be conceptualized as a continuum model comprising categorizations of uncomplicated (mild) and complicated (moderate and severe) courses. Psychosocial factors require more attention.
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