CHAPTER 13: KATZ INDEX OF INDEPENDENCE IN ACTIVITIES OF DAILY LIVING

Description

The Katz Index of Independence in Activities of Daily Living, by Katz, Ford, Moskowitz, Jackson, and Jaffe (1963), is an outcome measure designed to quantify an individual’s capacity to engage in basic activities of daily living (B-ADLs). Through assessment, functional status is determined by the clinician as he or she observes the person perform 6 activities related to (1) feeding, (2) continence, (3) transferring, (4) going to the toilet, (5) dressing, and (6) bathing. The Katz Index employs a unique Guttman-like hierarchy that follows the pediatric development model which argues that as a child matures, the simplest activity which is eating, is mastered first, followed by continence, then transferring, toileting, dressing, and bathing, in order of increasing complexity; thus as a person ages or experiences illness and performance is lost, it is lost in the reverse order from bathing to eating (LaPlante, 2010). The assessment uses a distinctive scoring system as well that delivers an item score as well as a total score expressed as levels of dependence from A, which is considered independent to G, representing the most of possible dependent grades (i.e., requiring assistance in all 6 activities). Although, there are only 6 items, there are several scoring possibilities in relation to the amount of assistance needed per task and the number of tasks where that assistance is needed (Strauss, Aguero-Torres, Kareholt, Winblad, & Fratiglioni, 2003). The quantitative notation of some type of assistance needed per task suggests more dependence. The Katz Index can be completed in less than 30 minutes; however, any single item can be completed in less than 5 minutes.

Psychometrics

Original research by its authors determined that the Katz Index had and inter-rater reliability of r = 0.95 and correlated with a mobility scale at 0.50 and a house confinement scale at 0.39. A later Guttmann analysis of 100 subjects found that the coefficients of scalability had a range of r = 0.74 to 0.88, suggesting that the index formed a successful cumulative scale (Brorsson, & Asberg, 1984; Katz, Downs, & Grotz, 1970; Katz et al., 1963). A Turkish translation also found high inter-rater reliability at r = 0.99 as well as high test–retest reliability (0.99), and moderate levels of internal consistency at α = 0.84 among an outpatient clinic population of n = 211 (Arik et al., 2015). A cross-sectional study by Gerrard (2013) of 13,507 skilled nursing facility subjects (average age: 81 years, majority White female) determined eating to be the easiest item and bathing the most difficult item confirming the developmental model discussed earlier. A study of 460 acutely admitted older patients (mean age 78 years) and their proxies exhibited moderate to good levels of overall agreement relative to Katz Index scores at 0.70 to 0.90, which increased as their Mini-Mental State Exam (MMSE) scores increased. For example, when subjects scored ≤ 15 agreement was 0.70, whereas for those with MMSE scores between 16 to 23 there was 0.79 agreement, and for persons with scores ≥ 24 there was 0.90 agreement (Pol, Buurman, de Vos, & Rooij, 2011). Two studies of the predictive validity of Katz Index (n = 124 and n = 106) for cerebrovascular accident (CVA) subjects, who were assessed by an occupational therapist, determined that 96 and 94% of those graded A to C on days 5 to 7 after stroke were discharged within 1 month, whereas 96% and 92% of those graded D to G stayed in the hospital longer than 1 month or had died, while 62% and 68% of subjects graded as G died within 1 month, suggesting that the Katz Index is a valid tool for early prognosis and rehabilitation planning of CVA outcomes (Asberg & Nydevik, 1991).

Advantages

There is a significant amount of research in support of the Katz Index and it requires no training or certifications for use in clinical practice. Several modifications also exist, such as the trichotomous scoring version (i.e., three levels of independence/dependence), as well one that uses as a simplified scoring system where each item is scored as either (1) independent or (0) with totals expressed along a numerical scale from (0 to 6). The Katz Index has been around since 1963 and can facilitate a common language because it is used by many health professions. The measure has been adapted and translated into numerous languages highlighting its cross-cultural relevancy as well.

Disadvantages

The presence of floor/ceiling effects can occur in scoring; thus, the appropriateness of its use should be considered relative to patient populations.

Administration

During assessment the clinician first observes and grades client performance relative to task items along a continuum of independent or dependent using standardized instructions and although independence typically suggests without supervision, direction, or active personal assistance, each item has specific inclusion/exclusion criteria. For example, in the bathing task independence is considered assistance only in bathing a single part (as back or disabled extremity) or bathes self completely, whereas dependence is assistance in bathing more than one part of the body, assistance in getting in or out of tub, or does not bathe self. Independence for the transfer item is the ability to move in and out of bed independently or move in and out of chair independently (with or without the use of mechanical supports), while dependence is assistance in moving in or out of bed and/or chair or does not perform one or more transfers (MacDowell, 2006). Item tasks are them summed along a hierarchical grading scale form (A) independent in all task to (G) dependent in all tasks as follows:

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