Validation of an Instrumental Device to Estimate the Risk of Falls and Frailty in Older People

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents the validation of an instrumental device (Oldfry) for assessing fall risk and frailty in institutionalized older adults, with comparison against established clinical tests (TUG and SPPB). The topic is relevant and the study is generally well organized; however, several methodological, analytical, and presentation issues should be addressed to strengthen the rigor and clarity of the manuscript.

1. Although the study is framed as a validation of an instrumental device, the technical description of the Oldfry system (sensor type and extracted signal features) is very missing. Providing more detail would improve transparency.

2.  It is not always clear how the raw sensor data are mapped to TUG and SPPB clinical scores. A clearer explanation or schematic describing this conversion process is needed.

3. The Introduction and Discussion cite several related studies using inertial sensors, but a more explicit comparison of Oldfry’s performance with these systems would strengthen the novelty and positioning of the work.

4. The Introduction should include a broader discussion of related devices and existing approaches, clearly outline their limitations, and explicitly describe how the proposed work improves upon and innovates beyond prior studies
5. For the 95% confidence interval ranges reported in the tables, it would be clearer to use “–” or “to” instead of “a” to denote the interval limits.
   
   
6. Abbreviations should be defined in full only at their first occurrence in the text and used consistently thereafter.
7. A previously published Sensors paper (https://doi.org/10.3390/s25102964) by the same author group reports Oldfry outcomes; therefore, the authors should explicitly clarify the relationship between the dataset and the distinct contribution of the present study.

 

Author Response

Dear Reviewers,

We would like to sincerely thank you for your valuable comments and constructive suggestions, which have significantly contributed to improving the quality and clarity of the manuscript. All modifications introduced in the revised version have been highlighted in yellow for ease of identification.

 

Reviewer 1

1. Comment:

The technical description of the Oldfry system is insufficient.

Response:

We thank the reviewer for this comment. In order to improve the transparency and reproducibility of the study, the technical description of the Oldfry device has been substantially expanded. Specifically, additional details have been included regarding the type of sensors, signal acquisition, preprocessing procedures, and system configuration. These modifications have been incorporated into the Description of the Oldfry device section.

2. Comment:

It is not always clear how raw sensor data are mapped to TUG and SPPB clinical scores.

Response:

We appreciate this insightful suggestion. The manuscript has been revised to provide a clearer and more detailed explanation of how raw sensor data are processed and translated into clinically interpretable TUG and SPPB outcomes. In particular, we have incorporated a detailed description of the data processing pipeline, including signal preprocessing, segmentation of movement phases, feature extraction, and mapping to clinical scores using a rule-based algorithm. This addition improves methodological transparency and eliminates the perception of a “black-box” approach.

 

 

3. Comment:

A more explicit comparison with other inertial sensor-based systems is needed.

Response:

We thank the reviewer for this valuable comment. In response, the Discussion section has been expanded to include a more explicit comparison between the Oldfry device and previously reported inertial sensor-based systems. The revised text highlights differences in terms of assessment approach, level of integration (multi-domain versus single-task), and diagnostic performance. In particular, we emphasize the ability of Oldfry to simultaneously estimate both TUG and SPPB outcomes within a single protocol, as well as its relatively high sensitivity compared with previously reported systems.

4. Comment:

The Introduction should include a broader discussion of related devices and existing approaches, clearly outline their limitations, and explicitly describe how the proposed work improves upon prior studies.

Response:

We appreciate the reviewer’s suggestion. The Introduction has been revised to include a broader and more structured discussion of existing sensor-based approaches and their limitations. Specifically, we now explicitly describe the main shortcomings of previous systems, such as their focus on isolated parameters, limited clinical interpretability, and lack of integration with standardized clinical tools. In addition, we have clarified how the proposed device addresses these limitations by providing an integrated, clinically aligned assessment based on TUG and SPPB, thereby strengthening the novelty and positioning of the present study.

5. Comment:

The notation of confidence intervals should be improved.

Response:

We thank the reviewer for this suggestion. The notation of confidence intervals has been revised throughout the manuscript to ensure clarity and consistency.

 

6. Comment:

Abbreviations should be defined at first use and used consistently.

Response:

We appreciate this comment. The manuscript has been carefully revised to ensure that all abbreviations are defined at their first occurrence and used consistently throughout the text.

7. Comment:

Clarify the relationship with the previously published Sensors paper.

Response:

We thank the reviewer for raising this important point. The relationship between the present study and our previously published work has been explicitly clarified in the Introduction. We now state that both studies are based on the same cohort; however, they address fundamentally different objectives. The previous study focused on identifying associations between clinical and functional variables and fall risk and frailty, whereas the present work is designed as a validation study evaluating the diagnostic performance, reliability, and agreement of the Oldfry device against established clinical reference tests (TUG and SPPB). Therefore, the current study provides complementary methodological evidence regarding the accuracy and reproducibility of the device, representing a distinct and necessary contribution.

We sincerely appreciate the reviewers’ comments, which have significantly strengthened the manuscript. We hope that the revisions satisfactorily address all concerns.

Reviewer 2 Report

Comments and Suggestions for Authors

This is a very interesting study addressing the development of precise devices for fall and frailty detection.Nevertheless, I have some comments and recommendations:

The manuscript may specify which tests or instruments were used to determine the level of cognitive impairment in the participants. These yools /assessments must be clearly described and referenced in the Methods section.

Frailty is commonly associated with weight loss and sarcopenya. However, most participants in this study presented a normal BMI. This apparent discrepancy should be explicitly addressed and discussed.

The reference of study 227 in the discussion section should be clarified. what this study refers or if it is an error in the text..

The paragraph in the Conclusions section about limitations and future research would be placed in discussion section. In addition, it should be emphasized that the effectiveness of objective assessment tools must also consider their cost_effectiveness, particularly when compared with simple and widely used clinical assessments.

Author Response

Estimados revisores,

Agradecemos sinceramente sus valiosos comentarios y sugerencias constructivas, que han contribuido significativamente a mejorar la calidad y la claridad del manuscrito. Todas las modificaciones introducidas en la versión revisada se han resaltado en amarillo para facilitar su identificación.

Comentario:

El manuscrito debe especificar qué herramientas se utilizaron para evaluar el deterioro cognitivo.

Respuesta:

Agradecemos al revisor su comentario. El deterioro cognitivo se evaluó mediante la prueba de Pfeiffer, que ahora se describe con mayor claridad en la sección de Métodos, incluyendo la referencia correspondiente. Esta aclaración mejora la transparencia de la metodología del estudio.

Comentario:

La fragilidad se asocia comúnmente con la pérdida de peso y la sarcopenia, pero la mayoría de los participantes tenían un IMC normal.

Respuesta:

Agradecemos al revisor su valioso comentario. Si bien la fragilidad suele asociarse con la pérdida de peso y la sarcopenia, es importante reconocer que se trata de un síndrome clínico multidimensional que no se define exclusivamente por el índice de masa corporal ni el estado nutricional. En adultos mayores, especialmente en poblaciones institucionalizadas, la fragilidad también puede presentarse en personas con un IMC normal o incluso elevado debido a factores como la disminución de la fuerza muscular, la movilidad reducida, los problemas de equilibrio o la obesidad sarcopénica. Por lo tanto, el IMC por sí solo puede no reflejar adecuadamente los componentes funcionales y fisiológicos de la fragilidad. Este aspecto se ha aclarado con mayor detalle en la sección de Discusión para contextualizar mejor nuestros hallazgos.

Comentario:

Aclarar la referencia 227.

Respuesta:

Agradecemos al revisor por haber detectado este problema. La referencia era un error tipográfico y se ha corregido en el manuscrito revisado.

Comentario:

Las limitaciones deben trasladarse a la sección de Discusión, y debe considerarse la relación costo-beneficio.

Respuesta:

Agradecemos su comentario. La sección de Conclusiones se ha revisado y la discusión sobre las limitaciones se ha reubicado en la sección de Discusión. En cuanto a la rentabilidad, reconocemos su importancia; sin embargo, este aspecto quedaba fuera del alcance del presente estudio y se considerará en futuras investigaciones.

 

Agradecemos sinceramente los comentarios de los revisores, que han enriquecido significativamente el manuscrito. Esperamos que las revisiones resuelvan satisfactoriamente todas las inquietudes.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have satisfactorily addressed the concerns raised in the previous review. I have no further comments.

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

I want to thank the authors to thei changes on the final manuscript due to my suggestions.