Brief Lower Body Functional Performance Questionnaire (Brief-LBFPQ) for independent older adults

Abstract Introduction The literature still lacks evidence about patient-reported outcome measures to fast screen the reduced physical performance of the lower body in older adults to be applied in any clinical setting as primary health care or without specific instruments in prevention campaigns, or even easy to be applied by phone. Objective: To develop a brief questionnaire to screen the lower body functional performance in community-dwelling older adults and to validate this new questionnaire with objective clinical tests. Methods A convenience sampling of 221 community-dwelling older adults was included in this cross-sectional study. The validity between Brief-LBFPQ and objective tests such as gait speed, Timed-Up and Go test (TUG), 5-Time Stand-to-Sit test (5TSST), and step test were assessed by multinominal logistic regression. Internal consistency was determined using Cronbach’s alpha and Test-retest reliability was determined using intraclass correlation coefficient (ICC) for numeral scale and Cohen’s Kappa for ordinal scale. Results Brief-LBFPQ was significantly associated with objective tests. All eight items from Brief-LBFPQ presented an absolute agreement with ICCs values above 0.7. Kappa values of Brief-LBFPQ items ranged from 0.6 to 0.83, showing substantial agreement and perfect agreement. Conclusion Brief-LBFPQ could be very useful in general clinic settings as it provides earlier screening of functional impairment in independent older adults, and consequently may allow an earlier intervention approach.


Introduction
Functional capacity is characterized by the ability of the individual to conduct activities of daily living (ADL) independently, 1 or the ability to maintain the physical and mental skills necessary for an independent and autonomous life, despite the presence of comorbidities.The study was approved by the Human

Research Ethics Committee of the Ribeirão Preto
Medical School (CAAE: 62209916.5.0000.5440)and followed the Helsinki protocol for studies with humans.
All participants gave written informed consent.

Internal consistency and test-retest reliability
To verify the internal consistency and test-retest reliability, the same 155 participants who responded

Questionnaire development and viability
The development phase of the Brief Lower Body Functional Performance Questionnaire (Brief-LBFPQ) involved the choice of the questions (Figure 1) that represent challenging tasks for the lower body, which are important for social inclusion and independence of older adults.It is important to reinforce that this questionnaire, different from other available questionnaires, has included an item related to the difficulty of getting up from the floor.
Therefore, the draft questionnaire with 8 questions was administrated to a sample of 66 community-dwelling older adults, as well as the choice of score in a pragmatic way, which included a scale using ratings of 0 (no difficulty), 1 (little difficulty), 2 (moderate difficulty) and  In the second phase, after Brief-LBFPQ application in 155 participants, 63 older adults were classified as having no impairment, 68 as mild impairment, 20 as moderate impairment, and 4 as having severe impairment.Table 3 shows

Results
Mean age, sex, weight , height and BMI are presented in Table 1.
In the first phase, Brief-LBFPQ was applied to 66 volunteers and 25 (33.3%) were classified as no impairment, 39 (52%) as mild impairment, two (2.7%) as moderate impairment, and no severe impairment was encountered.

Discussion
The results of this study demonstrated that the Brief-LBFPQ was associated with lower limb physical function tests widely administrated in the older population.
The validity properties of the questionnaire were confirmed through the significant associations with objective functional tests.Also, the Brief-LBFPQ internal consistency reliability was good to excellent.

Conclusion
The usage of adequate functional assessment instruments in population inquiries can support strategies for providing effective care for older adults that privilege actions focused on the reality of this population group.In addition to this, our Brief-LBFPQ could be very useful in general clinic settings as it provides reliable information about the lower limb functional status of healthy older adults, enabling an earlier screening of function impairment, and consequently an earlier intervention approach.In advance, our study group is already assessing new data to elucidate the practical use of the Brief-LBFPQ that will be presented in future studies.
function assessments were carried out in the Laboratory of Assessment and Rehabilitation of Equilibrium (L.A.R.E.) of the Department of Health Sciences at the Ribeirão Preto Medical School, Universidade de São Paulo, Brazil.The sociodemographic characteristics assessed were sex, age, stature, body mass, body mass index (BMI), and years of education.For these in-person assessments, convenience sampling was used, which included 221 participants.The physical function assessments included Timed Up and Go (TUG), 5TSST, gait speed, and forward step test, which were performed in random order.Participants were asked to rest for at least 30 seconds between the trials.The TUG test is a clinical test widely used to assess balance and walking ability in older populations.20Participants were observed and timed in seconds, while they stood up from an armed chair, walked at their usual pace for a distance of three meters, turned 180 degrees, walked back to the chair and sat down.A reduced time to complete the test indicates a better performance.The test was repeated three times to obtain the mean.Although it is very simple, the TUG test is highly recommended, since it includes the basic everyday movements and daily life tasks (standing, walking, and turning) and contains valuable components.20The TUG has shown excellent test-retest reliability (ICC = 0.91 to 0.92).The 5TSST is a clinical test that measures the time needed to stand up and sit down five times as fast as possible with arms crossed over the chest.Despite its apparent simplicity, going from a sitting to a standing position reflects an important skill in older people, which involves a sequence of multiple tasks.Also, the inability to perform the test may lead to institutionalization and impaired function and mobility in activities of daily living.21The test was repeated twice to obtain the mean.The 5TSST has shown excellent test-retest reliability (ICC = 0.81) and moderate validity to measure lower limb muscle function (r = -0.48 to -0.57).22 Gait speed (m/s) was assessed over 8 meters and the walking time was recorded.To eliminate the acceleration and deceleration components, the volunteers were instructed to begin walking 1.5 m before the beginning of the course and to finish 1.5 m after the end of the course, being 5 meters the real course of the test.The test was repeated three times and the mean of the gait speed of the three trials was used.The gait speed has good reliability (ICC = 0.88 to 0.97) and validity (r= 0.53 to 0.74) for community-dwelling older people according to Kim et al. 23 The forward step test was performed by asking the volunteers to climb up the 10-cm step using the dominant lower limb and go down in front of the step with the contralateral lower limb as quickly as possible.The height of the step increased by 10 cm at each phase, reaching the maximum height of 50 cm.If the volunteer was not able to climb the requested step height, the height was decreased by 5 cm and a new attempt was made.6 For each height requested, only one attempt was performed, and the final test score corresponded to the highest step that a participant could climb without assistance.The step test has shown excellent test-retest reliability (ICC = 0.94) 6 and moderate validity to measure knee extensor strength (r = 0.60).24 FISIOTERAPIA EM MOVIMENTO Physical Therapy in Movement Iosimuta NCR et al.Fisioter Mov.2023;36:e36111 4 to the Brief-LBFPQ by phone were recontacted with an interval of seven days, and the Brief-LBFPQ was administrated again.Although the sample was obtained by convenience, the size was greater than the minimum number proposed by the COSMIN checklist, which is greater or equal to 100 participants.25 Therefore, the Brief-LBFPQ was applied twice by phone, with an interval of seven days between test and retest to analyze the internal consistency.Statistical analysis Sample characterization was provided as mean, standard deviation, frequency, and percentage.Validity was evaluated by multinominal logistic regression between the categories of Brief-LBFPQ (as dependent variables) and the scores of TUG test, 5TSST, gait speed, Validity of Brief-LBFPQ The validation study was conducted in the remaining sample of 155 community-dwelling older adults who completed the in-person physical function assessments on day one.For this phase, the participants were contacted by phone at an interval of two weeks after the in-person assessments to answer the Brief-LBFPQ.The validity of this questionnaire was investigated by evaluating the validity of Brief-LBFPQ in association with other clinical tests, such as gait speed, TUG, 5TSST, and step test.
and step test (as independent variables), and by the determination of the odds ratio and the respective 95% confidence interval (95%CI).Confounding variables (age, sex, BMI, years of education) were included in the multinominal logistic regression model to analyze whether these covariates could interfere with the association.Internal consistency was assessed using Cronbach's alpha, and the chance correlated agreement reliability for one hundred and fifty-five participants at two time points was calculated using Cohen's unweighted Kappa statistic for the ordinal scale and Intraclass Correlation Coefficient (ICC) was applied for numerical scale.Cronbach's alpha was interpreted according to the scale of α ≥ 0.9 = excellent; 0.7 ≤ α > 0.9 = good; 0.6 ≤ α > 0.7 = acceptable; 0.5 ≤ α > 0.6 = slightly acceptable; and α < 0.5 = unacceptable.The Kappa coefficients were interpreted using the criteria outlined by Landis and Koch,26 summarized as follows: < 0 (poor agreement); 0-0.2 (slight agreement); 0.21-0.40(fair agreement); 0.41-0.60(moderate agreement); 0.61-0.80(substantial agreement); 0.81-1.0(almost perfect agreement).In addition, the standard error of Kappa (SE) and the corresponding 95%CI for each Kappa value obtained were also computed.The statistical analysis was performed using the SPSS 15.0 (SPSS, Chicago, IL, USA).The level of significance was set at 5% (p ≤ 0.05).

Table 2
details the internal consistency and testretest reliability for the data analysis of second phase of the estudy (n = 155).According to interpretations of Cronbach's α reliability coefficients, six items have excellent reliability and the other three dimensions have good reliability.Henceforth, ICC was used as a statistical tool to confirm the reliability of the items from Brief-LBFPQ.ICCs values above 0.7 were considered as high, which shows that all items from Brief-LBFPQ presented absolute agreement.
-LBFPQ = Brief Lower Body Functional Performance Questionnaire; Item 1 = step up and step down on the bus ; Item 2 = walk 800 meters; Item 3 = lay down, sit and stand up; Item 4 = get in and get out of the car; Item 5 = squat; Item 6 = get up from the floor; Item 7 = do households chores (to sweep, do the laundry, hang clothes to dry); Item 8 = go up and down stairs.K = Kappa coefficient; SE = standard error of Kappa; CIk = confidence interval from Kappa coefficient; α = Cronbach's Alpha; ICC = intraclass correlation coefficient (95%CI).*p < 0.001 according to Kappa test-retest reliability; #p < 0.001 according to Cronbach's Alpha.

Palavras-chave: Avaliação geriátrica. Nível de saúde. Desem- penho físico funcional.
between the impaired results of these tests and a reduction of lower limb muscle strength.6,8 4,3The poor performance of functional activities (i.e.walking, climbing stairs, sitting down, and standing up) has been related to lower limb muscle weakness (LLMW).4-6Several clinical tests have been recommended to assess LLMW, such as the 5-Time Standto-Sit test (5TSST), 7 gait speed, and step test, since there is an association 14 Despite the number of general self-reported questionnaires for functional capacity, the validity method of these questionnaires has not been performed through objective tests as those used to evaluate the aforementioned LLMW.Understanding the validity of functional questionnaires based on clinical tests may help health professionals (i.e., physiotherapists, physical educators, and occupational therapists) to elaborate physical exercise training centered on each patient's need.The convergent validity of SMFA, which has 46 items to assess the functional level of patients with musculoskeletal disorders, had an excellent correlation with health status through the Short Form-36 (SF-36).15 The LEFS, with 20 items applicable to patients with musculoskeletal conditions, is correlated with SF-36.16 The FAQ, with 34 items that include physical, psychological, social, and sexual function, days off because of health, and health satisfaction in adults and older adults, had convergent validity with Lawton and Brody scale, Mini-Mental State Examination, and executive function.17 Additionally, the GLFS-25, with 25 items that assess lower limb function, also had convergent validity with Lawton and Brody scale.14 Therefore, this study aimed to develop a brief questionnaire to screen the lower body functional performance in community-dwelling older adults and to validate this new questionnaire with objective clinical tests.e os testes objetivos como velocidade da marcha, Timed-Up and Go (TUG), teste de levantar e sentar 5 vezes (TLS5x) e teste do degrau foi avaliada pela regressão logística multinominal.A consistência interna foi determinada pelo alfa de Cronbach e a confiabilidade teste-reteste foi determinada pelo coeficiente de

Table 3 -
Functional tests according to categories of the Brief-LBFPQ line, the identification of mild impairment of lower body functional performance justifies referring older adults to a health promotion program and, consequently, may prevent them to get worse over time.

Table 4 -
Association between the Brief-LBFPQ classifications and scores of TUG, 5TSST, gait speed and step test (n = 155) Brief-LBFPQ = Brief Lower Body Functional Performance Questionnaire; OR = odds ratio; CI: confidence interval; TUG = Timed Up and Go; 5TSST = five-time stand-to-sit test.aModel adjusted for age, sex, body mass index and years of education.*p < 0.05 according to the multinominal logistic regression analysis.Also, the Brief-LBFPQ was developed to detect earlier physical function deficits in independent older adults, thus, future studies must evaluate the psychometric validity of Brief-LBFPQ in different with different health conditions, i.e., oldest adults, Parkinson disease, frailty syndrome.