Since balance is a multifactorial function, a single test cannot be sufficient for its evaluation. Different types of tests measure diverse aspects of postural control. Balance tests can be grouped based on their types. Static standing balance tests evaluate maintenance of balanced state while standing on different support platforms. However dynamic standing balance tests evaluate continuity of balanced state during movements requiring weight transfer [16, 29]. Sensorial manipulation tests assess various positions of the trunk and head, eye movements, and also limitations imposed on visual, vestibular, and somatosensorial functions. However tests evaluating functional balance are related to the scales of mobility and gait, sitting and standing, walking, and stepping over objects which involve ability to perform tasks requiring mobility of the body as a whole [16]. POMA is one of the functional scales used to assess fall risk and functions of postural balance which had been developed firstly in a study where falls had been evaluated prospectively [9].
Before the development of POMA, conventional approaches for the evaluation of mobility disorders were focused on either standard neuromuscular assessment methods (i.e., manual muscle test) or analytic estimations such as computerized gait analyses, while performance ability of the individuals was not rated. Tinetti proposed an assessment method based on direct observation of composite maneuvers involving ability of the individual to move safely within the boundaries of his/her vicinity. This method examines components of mobility which an individual might strive hard to perform during his/her daily living activities, and >investigates responses to varying degrees of difficulties imposed by certain maneuvers and at the same time helps to determine potential regulatory interventions such as organization of exercises and/or correction of domestic conditions so as to increase patient’s mobility [1, 9, 10]. POMA is an easy-to-use evaluation scale which can be completed after a few trials within less than 15 min and requires not more than a chair and a chronometer [30].
As is the case in other fields of rehabilitation, to obtain accurate and objective measurements from functional scales used in the evaluation of fall risks and balance impairments, these scales should have certain clinometric properties [8, 15, 31]. Reliability, validity, and sensitivity to change lead the way among these required characteristics. Implementation of the scales for diverse population groups requires, in addition to accurate translation cross-cultural validity, interpretation of the original scale in easily comprehensible terms for the target population and culture [8, 15, 31, 32]. During the process of cultural adaptation phase implemented after the Turkish translation of POMA, appropriateness of the terms used was examined. At this phase the translation of item 7 (“eyes closed at maximum position #6”) of the balance subscale posed a problem. At item 6 standing balance against a slight nudging is tested, and testing of the item 7 is required in case the subject has obtained the best score from testing in item 6. Therefore if the item 7 is translated into Turkish merely as “gözler kapalı (eyes closed),” it might mean testing individual’s balance against nudging while eyes closed. However when the Tinetti’s original text is reviewed, this item does not test individual’s balance when his/hes eyes closed, but it evaluates his/her standing balance. Therefore the translation of the item 7 was corrected as “standing balance while eyes closed.” In the English version of the scale, measurement units “inch” and “feet” are used. When these units are converted to centimeters and meters used in our country, whole numbers cannot be obtained. Therefore complying with the recommendations of the translation committee, values were expressed in both measurement units, and included in the relevant items in order to be faithful to the original version and render the scale more comprehensible.
Interrelated items of the scale assessing the same functional parameters (i.e., gait or balance) and each item which represents the conceptual frame to be evaluated in a way demonstrate internal consistency of the scale [33]. In our study, internal consistency of balance and gait subscales of POMA was calculated using Cronbach’s α coefficient which was 0.83 for balance, 0.72 for gait subscales, and 0.88 for the total score. These estimates demonstrate improved internal consistency of the POMA scale. In the literature any study estimating the internal consistency of POMA scale has not been encountered.
With prolongation of life expectancies, individuals are living longer senescent periods. Since during this relatively longer duration of time the elder people will be probably monitored by different physicians at various time spans, intra- and interrater reliabilities of the scales used should be established. POMA was firstly developed in 1986, and it was then applied on 15 ambulatory participants by two separate assessors and interrater reliability was evaluated. These two assessors were ≥90% in consensus for the scores assigned to the participants [9, 10, 15]. Besides, the POMA scores assigned to the patients were found to be correlated with parameters of musculoskeletal system and neurologic variables (muscular strength of the lower extremities, lumbar extension, neck examination findings, and self-reported mobility status of the patients). In our study, we calculated intraclass correlation coefficient for the study of inter- and intrarater reliability studies, and determined intrarater ICC values for subscale scores of balance (0.86), gait (0.80), and total score (0.86), respectively. ICC values of ≥0.70 are acceptable, and the values we obtained prove the reliability of the Turkish version [34]. In three separate studies involving old population where interrater reliability was tested, higher interrater ICC values of 0.75 and 0.97 were found [30, 35–37]. Another study reported higher ICC values (>0.80) for both intra- and interrater reliability of the POMA scale in Parkinson’s disease [38]. In patients with amyotrophic lateral sclerosis, intra- and interrater reliability of the balance subscale were found to be excellent as assessed by ICCs (>0.90) [39].
The Test–retest reliability method means testing the scale used at short or long intervals depending on the components of the scale. For tests evaluating physical performance, instrument usage, and measurement of strength, this time interval should be at least 7 days. For test–retest correlation, usage of intraclass correlation method is advised. The test–retest correlation coefficient should be at least 0.80. Some authors reported that a reliability coefficient of 0.70 might be sufficient [34]. In related articles, ICC values for test–retest reliability of POMA scale were found to be 0.88 [36] and 0.93 [40] for total and balance subscale scores, respectively. In our study ICC values for test–retest reliability were above 0.80 (for balance subscale scores 0.88, CI 95% 0.83–0.92; gait subscale scores 0.92, CI 95% 0.87–0.94; and total score 0.94, CI 95% 0.90–0.95).
To demonstrate the validity of POMA scale, the BBS scale developed for the assessment of balance impairment in the elderly with its proven validity and reliability of the Turkish version was used [21–23]. A very significant positive correlation was noted between POMA and BBS total scores (r = 0.86) and also balance (r = 0.84) and gait (r = 0.77) subscale scores. Previous studies conducted by Berg et al. [22, 23] also arrived at a similar conclusion (r = 0.91).
TUGT is used widely in the assessment and monitorization of functional mobility in the elderly. In our study, as an another indicator of validity, the correlation between POMA and TUGT scale which is an important tool in the evaluation of risks of fall and can be used in the assessment and monitorization of functional mobility, was investigated. A very significant negative correlation was found between total score, and also balance and gait subscales of POMA with the corresponding parameters of TUGT. This negative correlation means that in case of improvement of postural balance of the individual, higher POMA scores are obtained together with decreased time intervals required for the performance of TUGT tasks. Similarly, in a study conducted by Faber et al. [30], a significant association was found between TUGT and POMA total scores (r = −0.68), balance (r = −0.66), and gait subscale scores (r = −0.56). Also, in a study conducted by Cho et al. [41] a significant negative correlation was detected between total scores of POMA and TUGT (r = −0.65) [41].
In conclusion, in this study, POMA-I scale which is used widely in the prediction of postural balance and risk of fall in the elderly was translated into Turkish, and appropriateness of the Turksih version for the Turkish population was demonstrated. Based on the results of this study, the Turkish version of POMA-I scale was shown as a reproducible, reliable, and a valid scale.
