More work is needed to identify anxiety in chronic low back pain patients

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A study in Spine has found that single-item questions have good sensitivity for depression (95%) but less so for anxiety (68%) among patients with chronic low back pain. It also found that the Hospital Anxiety and Depression Scale (HADS) and Hopkins Symptoms Checklist (HSCL) have 58% and 67%, respectively, sensitivity for anxiety among this group of patients. This suggests that more work is needed to identify more sensitive instruments to screen for anxiety in patients with chronic low back pain.

Silje Endresen Reme (Uni Health, Uni Research, Bergen, Norway) and others write: “Recent findings have indicated that one simple questionnaire might be enough to screen for depression in different chronic pain populations when a validated questionnaire was used as the gold standard.” However, they add that these results need to be tested “with a diagnostic interview as the gold standard”. Therefore, they compared the sensitivity of two single-item questions for identifying depression and anxiety, respectively, among patients with chronic low back pain with two longer widely used questionnaires (HADS and HSCL), using the Mini-International Neuropsychiatric Interview (MINI) as the gold standard diagnostic interview.

In a population of 564 patients with chronic low back pain (all on sick leave because of their back pain), using MINI, Reme et al found that 21 patients (4%) had depression and 69 (12%) had anxiety. However, they write: “According to HADS, 18% (100) of the patients scored above the cutoff for depression and 23% (125) scored above the cutoff for anxiety. According to HSCl, <29% (156) score above the cutoff for depression and 20% (111) scored over the cutoff for anxiety. Based on the two single screening questions, 46% (243) reported to have been bothered by depression while 22% (115) reported to have been bothered by anxiety during the last month.”

The results of the study also indicated that the single screening questions showed 95% sensitivity and 56% specificity for depression and 68% sensitivity for depression and 85% specificity for anxiety. Reme et al report that for both depression and anxiety, the single-item questions had “perfect sensitivity” for certain diagnoses of the respective conditions. For example, the single screening question correctly identified all patients with panic disorder, all patients with post-traumatic stress disorder, and all those with obsessive compulsive disorder.

According to the authors, the longer questionnaires had similar or poorer discriminating abilities as the single screening question for depression—the HADS had 91% sensitivity and 85% specificity while the HSCL had 86% sensitivity and 74% specificity for the condition. They add that in terms of anxiety, the HADS had poorer discriminating abilities than the single screening questionnaire (58% sensitivity and 83% specificity) but the HSCL had similar abilities (67% sensitivity and 87% specificity).

Reme et al comment: “Pain-related fear has been found to be more disabling than the pain itself in chronic back pain and the disabling consequences of anxiety are as severe as depression when combined with chronic musculoskeletal pain. This suggests that screening for anxiety disorders may be as important for depression in chronic low back pain. Given our results, additional work is needed to identify more sensitive information instruments to screen for anxiety.”

However, they add that although the single screening question for anxiety was less sensitive than the depression question (and “therefore, may be insufficient as a screening tool in clinical practice”), it could be used in epidemiological studies because it “showed similar or better discriminating abilities than the two longer questionnaires”. They add that the single screening question for depression could replace longer screening instruments to identify potentially depressed patients “particularly in cases where length is a concern.”

“Psychological disorders, such as depression and anxiety, are important prognostic indicators in chronic low back pain. Simple screening tools able to identify these at an early stage, could help ensure proper treatment for the patients who screen positive, and could thus prevent long-term disability. The results of this study are therefore an important step towards the development of such tools, especially for depression. For anxiety, further work is needed to develop a more sensitive screening tool. Considering the little attention anxiety has received in previous literature on chronic low back pain compared to depression, a good screening tool to identify anxiety is particularly important.”