Identifying psychological contributions to chronic pain complaints with the MMPI-2: the role of the K scale.

Although the 1-3/3-1 Minnesota Multiphasic Personality Inventory (MMPI) code type is traditionally interpreted as suggesting that somatic complaints are caused or exacerbated by psychological factors, prior research has raised questions about the validity of this interpretation for chronic pain patients. This study examined alternative strategies for using the MMPI to identify psychological contributions to chronic pain complaints. A sample of 125 chronic pain patients completed the MMPI-2. They were also rated by clinical staff on a set of descriptive statements reflecting psychological features that can contribute to physical complaints. MMPI patterns that are traditionally used to identify these features, such as the 1-3/3-1 code type, were not related to the ratings. A relation was found between scores on the K scale and the ratings, where patients with higher scores on the K scale (T > or = 56) received ratings suggesting less of a psychological contribution to their pain complaints. The implications of the findings for understanding the nature of the K scale are discussed.