Does Disability Correlate With Impairment After Hand Injury?

Background: Any loss or deviation in body function and structure is considered impairment, whereas limitations on activities are fundamental to the definition of disability. Although it seems intuitive that the two should be closely related, this might not be the case; there is some evidence that psychosocial factors are more important determinants of disability than are objective impairments. However, the degree to which this is the case has been incompletely explored.

Questions/purposes: The purpose of this study was to determine if disability (as measured by the Disabilities of the Arm, Shoulder and Hand [DASH] and the Michigan Hand Questionnaire [MHQ]) and pain intensity correlate with impairment (as measured by the American Medical Association [AMA] impairment guide). Secondary study questions addressed the effect of pain intensity and symptom of depression on predicting disability.

Methods: Impairment and disability were evaluated in a sample of 107 hand-injured patients a mean of 11 months after injury. Impairment rating was performed prospectively. From the patients who came for therapy, they were invited to fill out the questionnaire and evaluated for impairment rating. Response variables of DASH, MHQ, and visual analog scale pain intensity values were collected at the same setting. Other explanatory variables included demographic, injury-related, and psychological factors (symptoms of depression measured with the Beck Depression Inventory). Initial bivariate and multivariate analyses were performed to determine correlations of disability and pain to impairment rating and other exploratory variables.

Results: Disability as measured by the DASH showed intermediate correlation with AMA impairment (r = 0 .38, beta = 0.36, p = 0.000). Together with gender, it accounted for only 22% of the variability in DASH scores. Similarly, MHQ score correlated with impairment rating (r = -0.24, beta = -0.23, p < 0.05). However, together with age, injured hand accounted for only 19% of the variability in MHQ scores. However, pain intensity did not correlate with impairment (r = -0.46, p > 0.05). Interestingly, pain intensity did correlate with the time passed from surgery but it was correlated with symptom of depression (r(2) = 0.10, beta = 0.33, p = 0.001).

Conclusions: The limited correlation between impairment and disability emphasizes the importance of factors other than pathophysiology in human illness behavior. These may include physical (pain, dominant injured hand) and conditional factors (time since surgery) or psychological factors such as depression and adapting; all mentioned can be considered as personal factors that may be different in each patient. So considering personal difference and any other condition except the impairment alone can help to better plan interventions and also diminish disability level.

Level Of Evidence: Level III, therapeutic study.