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Abstract
Introduction Knee osteoarthritis (OA) is a chronic condition affecting joint function. Regular physical activity can enhance functional capacity and reduce pain. However, there is a scarcity of studies relating to knee OA during the COVID-19 pandemic, particularly its impact on symptoms and quality of life.
Methods This analytic cross-sectional study design will recruit participants aged 40 and above from Metro Manila with knee pain and COVID-19 history. The Filipino version of the Knee Injury and Osteoarthritis Outcome Score and International Physical Activity Questionnaire-Short Form will be used to assess the mediating variables.
Analysis The study will employ descriptive and regression analyses for data analysis and follow the Strengthening the Reporting of Observational Studies in Epidemiology statement for reporting the data.
Ethics and dissemination This study has received ethical approval from the Ethics Review Committee of the College of Rehabilitation Sciences. Study results will be disseminated through peer-reviewed journal publications and conference presentations to ensure accessibility to healthcare professionals and stakeholders, contributing to the advancement of knee OA management in post-COVID settings.
- REHABILITATION MEDICINE
- Quality of Life
- Knee
- COVID-19
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STRENGTHS AND LIMITATIONS OF THIS STUDY
The study uses validated and culturally adapted tools, such as the Filipino version of Knee Injury and Osteoarthritis Outcome Score and International Physical Activity Questionnaire-Short Form, to ensure relevance and accuracy for the target population.
A purposive sampling method will be employed, which may limit the generalisability of findings beyond the selected barangay health centers in Metro Manila.
Reliance on self-reported questionnaires introduces potential biases, such as social desirability and recall bias, which could affect the accuracy of the data collected.
The recruitment of participants is planned to meet the recommended sample size of 150, but achieving this target may depend on participant availability and willingness to participate.
The exclusion of participants without verified COVID-19 histories could impact the representativeness of the sample and limit the breadth of findings.
Introduction
Background
Knee osteoarthritis (OA) is a chronic disease mainly affecting the joints, leading to pain, stiffness and decreased functional capacity. Because of this, knee OA patients are prone to marked functional deficits affecting their posture, balance and gait. The vast majority of older adults diagnosed with knee OA spend the day lying or sitting and have very minimal dynamic or locomotor activities. Regular physical activity can increase functional capacity by reducing pain and improving movement behaviour.1 The knee is the most common site for OA in older adults, and it manifests with joint symptoms, structural pathology, or both coexisting simultaneously. Primary symptoms involve knee pain and stiffness, loss of knee motion, and quadriceps weakness.
COVID-19 was declared a pandemic on 11 March 20202 by the WHO and officially ended on 5 May 2023.3 This leads to the lockdown and enhanced community quarantine (ECQ) of Metro Manila from 14 March 2020 to 30 April 20204 wherein there were restrictions on movement and means of transportation, tightly regulating business operations, providing food and basic amenities, and increased uniformed personnel presence. During the period of 4 August 2020 to 18 August 2020, a lighter and less stricter form of this called the modified enhanced community quarantine (MECQ) was then implemented followed by another ECQ period from 29 March 2021 to 4 April 2021.5 This mode of lockdown influenced the state of health, social relations and other activities. During the lockdown, it was reported that a continuous decrease in physical activity is associated with increased pain and loss of joint function. About 4.6% to 12.1% of COVID-19 patients frequently experience joint pain within the first year of infection. These symptoms are analogous to those seen in the early stages of OA development. Endothelial and adipose tissue dysfunctions, along with neuronal sensitisation, were shown to be highly similar in COVID-19 and knee OA patients.6 Knee OA patients showed a faster deterioration in pain score compared with hip OA patients during lockdown, which suggests that loss of activity has a higher impact on knee OA.7 The impact of COVID-19 on patients with knee OA is further examined by a survey of 1800 participants across 7 European countries, of which~17% had OA, about 46% reported inability to continue exercising, about 76% reported increased pain, over 46% reported a decrease in self-perceived health status during lockdown and 40% reported gaining weight during lockdown.8
Physical activity can play a crucial role and moderating effect on patients’ quality of life (QoL), especially among individuals with various medical conditions, such as knee OA. Exercise is one of the most discussed and controversial nonpharmacologic management strategies for knee OA.9 Patients with hip or knee OA who engaged in physical activity reported less pain, improved physical function and a higher health-related QoL than OA patients with a less active lifestyle.10 It has been established that light to moderate regular physical activity offers both preventive and therapeutic benefits for individuals with knee OA.
Physical function is one of the most significant domains evaluated in health-related quality of life (HRQoL), and assessing mobility capacity from the patient’s perspective could be highly beneficial.11 COVID-19-related outcomes presented a decline in physical function, peripheral and respiratory muscle strength, pulmonary functions, and physical performance.12 In addition, there is a decrease in activities of daily living after the COVID-19 infection, resulting in a loss of autonomy and independence for the patients, negatively affecting their QoL.13 In 2021, an urban cohort of people in the Greater Boston Area was assessed to explore the impacts of COVID-19 on individuals with systematic knee OA. Concerning physical activity, some individuals were able to maintain or recover to prepandemic levels, whereas other individuals showed decreased levels of physical activity several months later.14 Limitations in physical function may be one pathway to developing other comorbidities among individuals with knee OA.
The onset of knee pain indicates a significant and long-term decline in one’s ability to do daily tasks. Recognising the high frequency of knee OA and its impact on physical functioning and QoL, developing preventative strategies should be a public health priority. Physical activity minimises pain, improves physical function and improves HRQoL in persons with hip or knee OA as compared with sedentary OA adult patients. An improved patient QoL may significantly affect their overall physical function.10
A moderating variable influences the direction and strength of the relationship between the independent and dependent variables.15 Mediators are referred to as behavioural, biological, psychological or social constructs that transmit the effect of one variable to another variable.16 Mediation assumes that a precursor variable, such as knee OA symptoms, has an association with a mediating variable, such as poor QoL, which in turn affects the outcome variable (physical function). The mediation model serves as the foundation for the study’s conceptual framework, which is displayed in figure 1.
Conceptual framework of the study. This figure illustrates the conceptual framework guiding the study, highlighting the relationships between knee osteoarthritis (OA) symptoms, quality of life (QoL) and physical function. It emphasises how these variables interact, particularly in the context of post-COVID patients, and sets the stage for understanding the mediating roles of QoL and physical activity.
Knowledge gap
The relationships between knee OA symptoms, QoL and physical functions have been extensively studied, and their bidirectional influence is well known. The emergence of COVID-19, on the other hand, adds a new layer of complexity to the lives of those with knee OA and raises new variables about how this global health crisis may alter or exacerbate these previously identified correlations in people with knee OA.
Prior studies have demonstrated that purposeful exercise reduces the symptoms of OA and improves physical function; however, the effects of daily or spontaneous physical activity outside of formal training on the physical functioning of patients with OA remain poorly understood.17 Furthermore, not much is known regarding the physical activity levels of people with OA during the pandemic. The recommended amount and compliance with current PA guidelines during the pandemic might not be followed.18
As a result, it is crucial to investigate how a history of COVID-19 may alter the relationships between knee OA-related symptoms, QoL and physical functions. The study will explore how these factors are affected by the involvement of a COVID-19 diagnosis in a patient with knee OA and expound on the following:
The effects of a COVID-19 diagnosis on presenting symptoms and physical functions of patients with knee OA.
The changes in the QoL and physical activity levels of a patient with knee OA during their diagnosis of COVID-19 and, in general, during the pandemic.
The comparison between the study’s conceptual framework before the pandemic and within the context of COVID-19.
Different adaptations and alterations are needed in current knee OA management to accommodate the changes stated above.
As the world grapples with pandemic challenges, it is vital to continue exploring these relationships to better educate the management and care of patients with knee OA in this specific environment.
Objective
The objective of the study is to examine the mediating role of QoL between the association of knee OA-related symptoms and physical function. Additionally, this study will explore the mediating role of physical activity between the relationship of QoL and knee OA-related physical function.
Encapsulated in this proposed study is quantitative research investigating the relationships between the variables presented. To answer the objectives, a mediation analysis model was used. Figure 2 shows the mediation paths matched with the objectives. The determined aims of the proposal are the following:
To examine the association between knee OA-related symptoms and QoL in individuals with knee OA (figure 2, Path a1).
To examine the association between knee OA-related symptoms and physical activity in individuals with knee OA (figure 2, Path a2).
To examine the mediating role of QoL in the association between knee OA-related symptoms and physical function in individuals with knee OA (figure 2, Path b1).
To explore the mediating role of physical activity in the relationship between QoL and physical function of individuals with knee OA (figure 2, Path b2).
To investigate the association between knee OA-related symptoms and decreased physical function in individuals with knee OA (figure 2, Path c).
Conceptual framework of the study with the mediation path. This figure provides a detailed depiction of the mediation paths associated with the study’s objectives. It outlines specific pathways: (a1) the association between knee osteoarthritis (OA)-related symptoms and QoL, (a2) the relationship between knee OA-related symptoms and physical activity, (b1) the mediating role of quality of life (QoL) in linking knee OA symptoms to physical function, (b2) the mediating effect of physical activity on the relationship between QoL and physical function and (c) the direct association between knee OA-related symptoms and decreased physical function.
Significance
The research outcomes contribute to multidisciplinary areas of physical therapy, exercise science and rheumatology. The study establishes the association between knee OA symptoms and physical function. Further, this study determines the mediating role of QoL between knee OA and physical function. Postpandemic, little is known about the experiences of knee OA who also had a history of COVID-19 infection; hence, this study will benefit patients grappling with knee OA, as the study provides a valuable resource. It empowers them with a comprehensive understanding of how physical activity influences their knee OA-related symptoms, physical functioning and overall QoL. The research also holds significant implications for the rehabilitation team, including physical therapists, exercise scientists and rheumatologists, to aid in their better understanding of the association among the different variables and make clinically appropriate decisions in managing knee OA patients with a history of COVID-19 infection.
Delimitation
This study will use an analytic cross-sectional design focusing on Filipinos diagnosed with knee OA who also have a history of contracting the COVID-19 virus during the mode of ECQ and MECQ starting from the lockdown of Metro Manila implemented on 12 March 2020 until 4 November 2021. This study is specifically tailored to individuals with a history of COVID-19 and diagnosed with knee OA; therefore, other joints commonly affected by OA and other types of arthritis and degenerative diseases will not be covered.
Participants representing a broad range of physical activity levels will be included in this study with low, moderate and high activity-level categorisations. Additionally, the screening of participants will follow the Altman Criteria for OA, which involves physical examination, radiographic findings and other additional criteria; hence, other methods of diagnosing knee OA will not be used. Furthermore, the COVID history of participants will also be gathered and assessed according to their severity, frequency and method of diagnosis (RT-PCR, swab test, etc.) along with COVID-19 vaccination history. Following the classification of COVID-19 severity for adults released by the Department of Health, certain criteria such as oxygen saturation, respiratory rate and clinical signs of severe respiratory distress might not be contextualised in our study. Incorporating the classification of COVID-19 severity of the Department of Health will make the reporting of the results inaccurate and unreliable. To assess the past severity of COVID-19, the researchers will consider hospitalisation due to COVID-19 and the presence of symptoms as determining factors of severity. Finally, participants will be assessed through five outcomes: pain, symptoms, activities of daily living, sport and recreation function, and knee-related QoL. The Knee Injury and Osteoarthritis Outcome Score (KOOS) will be used to acquire the specific data from the participants.
Methods
Study design
This study will employ an analytic cross-sectional design to investigate the relationships between physical activity, QoL, knee OA-related symptoms, history of COVID-19, and physical function. An analytic cross-sectional design would enable the researcher to observe and examine factors associated with a particular variable of interest at one point in time, getting precise and specific results per variable investigated. The study uses a mediation-mediator analysis model to determine the potential mediating effect of QoL between the stated variables. As such, the data will be reported following the Strengthening the Reporting of Observational Studies in Epidemiology statement.
Participants/study selection
This study will recruit individuals aged 40 and above residing in Metro Manila with knee pain or soreness using the purposive sampling technique. Recruitment criteria are established to ensure the participants qualify for the study. Inclusion is based on the number of profiled individuals with OA and the proportion of those diagnosed with knee OA. The sample size for this study was calculated based on the requirements for conducting a mediation analysis. Power analysis was used to determine the minimum sample size necessary to detect a significant indirect effect (ie, the mediation effect) with a desired power level of 0.80 and a significance level of 0.05. The formula used to calculate the sample size for mediation analysis is based on the effect size, the number of predictors, and the desired power (see figure 3). Given that the desired power is 0.80 and the significance level is 0.05, we assumed a medium effect size for the mediation model. Using these parameters, the required sample size for this study is approximately 150 participants to ensure adequate power for detecting significant mediation effects.19 In case of unforeseen issues with recruitment, certain mitigations will be done.
Formula for sample size calculation. This figure presents the formula used for calculating the sample size necessary for conducting mediation analysis in the study. The calculation is based on a power analysis aimed at detecting significant indirect effects, with parameters set to a desired power level of 0.80 and a significance level of 0.05.19
The researchers will use the Altmann criteria for knee OA (see table 1).20 Each member of the population will be assessed by a research assistant that holds a Physical Therapy Professional Regulation Commission (PRC) License using the criteria to ensure that they are qualified to be part of the study. All eligible participants will be asked to answer the self-reported questionnaires provided by the researcher, and will then be invited to the next step of the recruitment process, a seminar about knee OA.
Inclusion and exclusion criteria to be used in the study
The use of purposive sampling, which involves recruiting participants barangay health centers in Metro Manila, poses a risk of selection bias as these recruitment sites may not fully represent the broader population of individuals aged 40 and above diagnosed with knee OA in Metro Manila; the findings may have limited generalisability to other settings or populations.
Setting
The research will focus on individuals with knee OA residing within Metro Manila. The researchers will recruit the eligible participants through collaborations with barangay health centers in Metro Manila to distribute the letters of invitation and surveys to participate in the study.
Tools
Filipino version of Knee Injury and Osteoarthritis Outcome Score (F-KOOS). The F-KOOS is a culturally adapted and validated version of the original KOOS, specifically for the Filipino population. It was translated and validated in a study to assess knee-related symptoms, physical function and QoL in Filipino individuals with knee OA. The Filipino version of the KOOS has been shown to have good reliability and validity for use in Filipino-speaking populations (see online supplemental appendix II). It consists of 42 items divided into five independently scored subscales: pain/pagkirot (9 items); symptoms/sintomas (7 items); activities in daily living/pang-araw-araw na gawain (17 items); function in sport and recreation/gampanin, isports at libangan (5 items); and knee-related quality of life/kalidad ng buhay (4 items).20 The mode of implementation involves self-report questionnaires, and the results are interpreted based on the scoring of the subscales, with higher scores indicating better knee-related QoL.21 The score calculation, together with the rest of the users’ guide for KOOS, can be obtained online.22
Supplemental material
International Physical Activity Questionnaire-Short Form (IPAQ-SF). The seven-item IPAQ-SF includes questions about the amount of time spent walking—both at a moderate and intense intensity—and sitting (see online supplemental appendix II). Given its ease of administration and comparable reliability and validity outcomes when compared with the long form, the short form may be chosen. The mode of implementation is through self-administration, and the interpretation of results is based on the categorisation of physical activity levels (low, moderate, high) derived from the responses to the International Physical Activity Questionnaire (IPAQ).
Procedures
The planned start date for this study is on March 2024, with the recruitment phase running until 17 May 2024. Following recruitment, data collection will commence on 1 June 2024 and conclude on 31 July 2024, encompassing participant surveys and seminars. The data analysis will take place in August 2024, with manuscript preparation from September 2024 to November 2024. The study is expected to be completed by December 2024, coinciding with the submission for publication and the presentation of findings. These timelines ensure the research is conducted methodically and adheres to ethical standards (see online supplemental appendix I).
Before proceeding with the data gathering, the study was subjected to ethical review and approval by the University of Santo Tomas (UST) College of Rehabilitation Sciences’ Ethics Review Committee. Participants will be recruited by disseminating a survey based on the Altman Criteria to determine their eligibility. Eligible participants shall be recruited in collaboration with barangay health centers within Metro Manila. A letter of intent will be sent to these institutions before gathering the participants. Eligible participants will be asked to sign a letter of consent confirming that they are aware of and willing to accept the conditions, benefits and risks of participation in the study. The study environment would be on-site, with questionnaires administered using pen and paper. The answering of survey questionnaires will be held in available areas within the premises of partner institutions and selected barangay health centers. Specific protocols implemented in the health centers will be followed prior to the implementation and data gathering procedure. COVID-19 vaccination history of the participants will also be asked and gathered along with the demographics. One-by-one, the participants will be called to answer the questionnaires. The questionnaire will request participants to provide demographic information such as age and gender and the symptoms they have experienced concerning their condition. The participants will then answer the following tools: F-KOOS and IPAQ-SF. The duration of the survey questionnaires shall last for approximately 15 min, containing self-administered questions. The researchers will help participants fill the questionnaires and handle any concerns or queries that may arise. Two 5 min breaks will be provided during this duration: one after answering the first two questionnaires and another after accomplishing all the questionnaires. The assigned academic staff will then collect and keep the answered questionnaires. The participants will then be invited to an educational seminar focusing on knee OA which will be conducted by the researchers (see table 2). The educational seminar entitled ‘Wag Kang OA’ will cover general information about knee OA such as its medical-surgical background, symptoms, prevention and intervention strategies. Licensed physical therapists will be present throughout the duration of the implementation. The seminar will be conducted within the same vicinity where the research will be conducted, specifically within the premises of the UST-affiliated clinics and selected barangay health centers. The hard copies of the questionnaires will be stored at the faculty author’s office, and all backup data and information collected will be securely stored in a 16-character password-protected Google Drive folder, which will only be accessible to the researchers. The data gathered will be stored for the duration of the study and shall be destroyed after 5 years through a paper shredder per the rules and provisions of RA 10173 or the Data Privacy Act.
Timeline of activities during the implementation day
Data analysis
Descriptive statistics will be used to describe the participants in the study. The mean and SD will be used for continuous variables, whereas the frequency and percentage will be used for categorical values. Both statistical techniques (Kolmogorov-Smirnov) and visual tools (normal probability plots) will be employed to determine whether each continuous variable follows a normal distribution. In cases where the continuous variables do not follow a normal distribution, they will be characterised by their medians (IQR).
Regression analyses will be used to estimate the relationships between knee OA symptoms, knee OA-related physical function and QoL. Additionally, potential confounding variables such as age and sex will be assessed for their impact on the regression coefficients. If a variable causes a change in coefficient greater than 10%, it will be considered a confounder and included in the multivariable regression analysis. Furthermore, mediation analysis will be conducted to examine the indirect association between knee OA symptoms and related physical function through QoL, both with and without adjustment for confounders. All analyses will be set at 0.5 alpha level.
In the cases of missing completely at random data, the researchers will address this using the single imputation method. Imputation through modelling is ideal as it minimises bias; alternatively, the missing data may be imputed using measures of central tendency (mean/median/mode). Reasons behind the missing data will also be noted. Sensitivity analyses will be conducted with the comparison between the results of the data analysis with and without outliers and the comparison between the effects of the utilisation of different imputation methods in the case of the missing data to be encountered in the study. Furthermore, post hoc sensitivity analysis methods will be added as needed.
Patient and public involvement
No patients were involved in the design or conduct of this study. However, the research team plans to disseminate the results of the study to the participants through a summary of findings. This will be done through follow-up communication, including email or direct delivery during future follow-up consultations or community-based seminars. Participants will also be informed about the publication of results through relevant channels such as local health centers and university-affiliated clinics.
Ethics and dissemination
Ethical approval
This study has been approved by the Ethics Review Committee of the College of Rehabilitation Sciences at the UST with Protocol Number SI-2023-019 (V.2). It will adhere to the principles outlined in the Declaration of Helsinki and comply with Good Clinical Practice guidelines as stipulated by the Philippine Health Research Ethics Board. The study will also follow Republic Act 10173, the Data Privacy Act of 2023, to ensure confidentiality and data protection for all participants.
Informed consent
Informed consent will be obtained from all participants before inclusion in the study. Participants will be provided with detailed information about the study’s purpose, procedures, potential risks and benefits. Consent forms will be signed by each participant prior to data collection.
Data storage and confidentiality
All data collected will be stored securely in password-protected files and only accessible to the research team. The physical copies of the questionnaires will be stored in the faculty author’s office, and all digital data will be stored in a password-protected Google Drive folder. Data will be retained for the duration of the study and for 5 years afterwards; after which, it will be securely destroyed in accordance with data protection laws.
Dissemination
Study findings will be disseminated through peer-reviewed journal publications and presented at academic and professional conferences to reach relevant healthcare professionals, policymakers and stakeholders. Participants will be informed of the study’s results through appropriate channels, and summary findings will be shared with the community involved in the study.
Ethics statements
Patient consent for publication
Footnotes
Contributors All authors made significant contributions to the design, execution and completion of the study. The conceptualisation and overall study framework were developed by the guarantor, DM, with input from all co-authors. Data collection was performed by the research team, with analysis and manuscript drafting led by ECGC. All authors actively participated in writing the manuscript, revising drafts and approving the final version for submission. The author identified as the guarantor of the study is DM. As the guarantor, he is responsible for the overall integrity of the research and ensures that all aspects of the work are conducted properly.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.