Daily diaries reveal influence of pessimism and anxiety on pain prediction patterns

Abstract

The match/mismatch model of pain prediction was tested with a group of rheumatoid arthritis patients (N = 227) in a natural setting. Daily diary measures of pain prediction and pain experience were obtained over 30 days. Results revealed a greater number of underpredictors (N = 147) than over predictors (N = 58) in our sample, with a minority (N = 22) overpredicting and underpredicting with equal frequency. Further, people modified their predictions to a greater degree after an over prediction than they did after an under prediction. As expected, anxious participants were less accurate and more prone to over predicting their pain than their less anxious counterparts. In contrast, participants who reported low levels of daily pessimism were more likely than their more pessimistic counterparts to under predict their pain. The findings suggest that people continued to under predict their pain despite repeated disconfirmations and that low levels of pessimism may have accounted for this pattern.

Keywords:

• pain predictions
• rheumatoid arthritis
• chronic pain
• daily diary

Notes

Notes

1. Rachman and Lopatka (1988) reported on a study involving arthritic patients, but did not elaborate on specific arthritis diagnoses.

2. Existing theory limited our ability to hypothesise about optimism and pessimism. Because prior research on over predictions and resistance to disconfirmation was primarily limited to the construct of anxiety, we chose not to offer a priori hypotheses of optimism and pessimism with regards to over predictions. All analyses reported in the results regarding optimism/pessimism and over prediction, then, should be considered post hoc.

3. In this test, the identifier given to each subject through Hypothesis 1 (i.e. over predictor or under predictor) had no bearing on the analysis. Instead, the analysis was concerned only with the error in pain predictions made following any over prediction or any under prediction.

4. To ensure that over predictions and under predictions were not simply oscillating around the cut-off we employed, we conducted a separate analysis labelling over predictions and under predictions only if they fell 20 points over the accompanying experience. We considered this an extremely conservative test, as it doubled the previously determined cut-off. Through this approach, the discrepancy between over predictions (n = 337) and under predictions (n = 982) widened.

5. In order to confirm that the findings were not a chance product of participants being identified as ‘over predictor’ or ‘under predictor’ as a result of simply predicting in one direction once or twice more than the other, we conducted the same analyses with participants who over predicted and under predicted at least five more times than the opposite prediction. Results indicated that 81 people were labelled ‘under predictors’ and 20 people were labelled ‘over predictors’ under this classification.

6. The authors would like to thank the reviewers of this manuscript who suggested that we conduct this important analysis.