O-Log Properties

Reliability: In a sample of 15 rehabilitation inpatients with a total of 75 O-Log scores, inter-rater reliability on the total O-Log was .993 while individual items ranged from .851 to 1.0 (Jackson, Novack, & Dowler, 1998). Cronbach's coefficient alpha for the O-Log segments on place, time and situation were .806, .865, and .834, respectively. The entire scale had a coefficient alpha of .922. These results indicate that the O-Log is a reliable instrument when used by multiple scorers and that it has internal consistency.

Concurrent Validity: Based on 554 observations on 68 patients with TBI, there was a significant correlation between the GOAT and O-Log scores (r=.901, p <.001; Novack, Dowler, Bush, Glen & Schneider, 2000). Minimum scores for both the GOAT and O-Log were significantly correlated with the admission GCS score (r = .456, p < .002 and r = .434, p < .003, respectively) and FIM score on admission to rehabilitation (r = .701, p < . 001 and r = .783, p < . 001, respectively). Assuming a cut-off score of 75 on the GOAT as a criterion for normal orientation, a comparable cut-off was established for the O-Log based on a score of 25 or better. This correctly identified 87% of those scoring above 75 on the GOAT and 82% of those obtaining scores below 76 on the GOAT. Estimation of PTA duration using the two scales based on 26 subjects proved to be almost identical. Assuming 2 consecutive scores above 75 on the GOAT and above 24 on the O-Log as marking the end of PTA, the correlation between the estimates of PTA for the two scales was r =.99, p <.0001.

Change in Orientation Over Time: Among 43 patients with TBI there was a steady linear improvement in orientation across 14 days of O-Log administration (Israelian, Novack, Glen, & Alderson, 2000). When groupings were established based on initial O-Log score upon admission to rehabilitation, it was apparent that all groups exhibited improvement in orientation by the time of discharge and at a similar pace, although those with the lowest orientation score on admission did not achieve the same level of orientation as other groups by discharge. Examination of responses to individual questions revealed variability in the difficulty of the items, with orienting to the name of the hospital and the date being the most difficult items, while orientation to the month, year, place, and city were the easiest. A template for improvement across 10 administrations of the O-Log has been established for both mild-moderate TBI and severe TBI in a rehabilitation setting (Alderson & Novack, 2002).

Predicting Outcome: The minimum O-Log score obtained during rehabilitation was significantly correlated with rehabilitation discharge FIM score (r =.575, p <.001) for 68 subjects with TBI. Based on a sample of 41 people with TBI participating in brief neuropsychological evaluation six months after injury, the minimum O-Log score obtained during rehabilitation correlated significantly with 7 cognitive measures (r = .278 to .376, p < .02), with the strongest association being evident on measures of memory functioning and attention (Dowler, Bush, Novack, & Jackson, 2000). There were also significant correlations noted with CIQ score at 6 months after injury and CIQ and DRS scores at 12 months post-injury (r = .28 to .395, p < .02). Severity of disorientation at admission to rehabilitation, time since injury when admitted to rehabilitation, and number of O-Log assessments are strong predictors of achieving orientation during a rehabilitation stay (Alderson & Novack, 2002). Administering the O-Log 3 versus 5 times a week, however, does not appear to have a significant effect on achieving orientation.

Qualitative Data: The O-Log also provides the opportunity to observe the patient when given logical cues that require at least minimal concentration and reasoning skills. These occasions can provide important clinical observations. Although it was not objectively evaluated in this study, it is not uncommon early in the recovery course for rehabilitation patients to provide answers that are grossly incorrect. For example, a patient might answer that it is 1985 when it is 1999. These responses have a significant impact on the GOAT score, but little impact on the O-Log score if the person is able to correct the error with a logical cue ("1985 was 14 years ago"). Equally telling is the situation in which a person provides a near accurate answer (such as being off by two days in providing the date), but cannot provide a correct response with a logical cue or through multiple choice.