This study investigated the most efficient means of measuring pain intensity and pain interference comparing ecological momentary assessment (EMA) to end of day (EOD) data, with the highest level of measurement reliability as examined in individuals with spinal cord injury.
EMA (five times throughout the day) and EOD ratings of pain and pain interference were collected over a 7-day period. Multilevel models were used to examine the reliability for both EOD and EMA assessments in order to determine the amount of variability in these assessments over the course of a week or the day, and a multilevel version of the Spearman–Brown Prophecy formula was used to estimate values for reliability.
Findings indicate the minimum of number of EOD and EMA assessments needed to achieve different levels of reliability (“adequate” > 0.70, “good” > 0.80 and excellent > 0.90). In addition, the time of day (either morning, midday or evening) did not impact the estimated reliability for the EMA assessments.
These findings can help researchers and clinician balance the cost/benefit tradeoffs of these different types of assessments by providing specific cutoffs for the numbers of each type of assessment that are needed to achieve excellent reliability.