PROGRESSIVE RESISTANCE EXERCISE IN WOMEN
WITH OSTEOARTHRITIS OF THE KNEE: A RANDOMISED CONTROLLED TRIAL
by Jorge,RTB, De Souza,MC, Chiari,A, et al.
The title of the trial has clearly, accurately and concisely described the purpose of the research and contains a similar level of information to many other trial report titles.
The report authors are located in Brazil and are employed by the Universidade de Sao Paulo’s Rheumatology Division with the exception of Artur da Rocha Correa Fernandes who is employed by the University’s Department of Diagnostic Imaging and Imperio Lombardi Junior who is employed in the University’s Department of Human Movement Sciences (Jorge et al. 2014).
The report’s abstract included a brief description of the objective of the randomised controlled trial which was to determine the effect of progressive resistance exercise on women with osteoarthritis of the knee. However whilst describing the purpose of the trial the abstract itself did not include any information as to why the research team considered the study was required.
The abstract provided a clear description of the eligibility of the randomised subjects including their numbers, age range and baseline pain levels. A detailed overview of the progressive resistance exercise programme including the target extensors, flexors, adductors and abductors was provided along with details of the exercise regime, measurement criteria and frequency. A detailed but concise comparison of the recorded results from the experimental and control groups was included in the abstract with a very brief conclusion.
The report authors introduced the rationale for the research study with a statistical overview of how osteoarthritis affects the world’s population and in particular the greater incidence amongst ageing females. A detailed overview of the effects of pain on mobility and quality of life has been evidenced by the authors’ comprehensive references to previous studies. A summary of the effects of weakness of the quadriceps muscles is provided together with a persuasive argument which supports the use of muscles strengthening exercise to improve range of movement and daily activities which impact on quality of life. Their argument is widely supported as the main purpose of treating osteoarthritis of the knee is to reduce pain and improve both the mobility of the knee and the quality of life for the individual (Farr,et al. 2010). Recently, the traditional approach to treatment by pain relieving medication alone has declined whereas resistance training exercise programmes and patient self-management training are generally considered more appropriate and beneficial than pharmacological intervention alone (Farr et al. 2010).
The introduction has developed the background to the problem well and links the recent move towards resistance training exercise to a lack of studies which address the role of hip muscles and the intensity of effort during exercise, thereby justifying their research during this particular study and to provide evidence for future studies.
In simple terms a randomised controlled trial is a study where participants are randomly placed into one of two groups one being the experimental group and the other being the control or comparison group. The experimental group contains the participants that receive the intervention that is to be tested and the control group receives an alternative and conventional treatment (Godin et al. 2011).
Two important features of a controlled trial which contribute to its credibility and value are randomising and blinding. Randomisation in this trial was achieved by electronic selection of eligible participants to either the experimental group or the control group, allocation being decided by sealed envelope and this appears satisfactory (Jorge et al. 2014).
Participants of controlled trials have to be blinded otherwise their behaviour and responses during the trial maybe compromised (Karanicolas et al. 2009). Blinding may be single where only the investigator is ‘blind’ to the subject for assessment or double where both the investigator and participant are ‘blind’ the participant being ‘blinded’ by not knowing if he is receiving the treatment under investigation or a standard treatment or placebo. Individual roles within a trial that should ideally be blinded are the participants, the clinicians, data collectors, data analysts and adjudicators (Karanicolas et al. 2009). In this trial the study team chose to single blind the assessor and not the participants, a decision which may attract suggestions of possible bias displayed by the participants albeit unintentional (Jorge et al. 2014).
The trial results recorded from both groups should be compared for differences to assess the effectiveness or otherwise of the intervention being tested (Kendal 2017). The trial report by Jorge et al. (2014) however lacks clarity during comparison as there is no detailed description of the intervention used with the control group participants, the report merely stating that participants in the control group were placed on a waiting list and received the same treatment following the end of the study (Jorge et al. 2014).
In order for randomised controlled trials to have both credibility and value in future clinical application there has to be a consistent approach both to the conduct and reporting of such trials. Absence of such important factors led to the introduction of Consolidated Standards of Reporting Trials (CONSORT) in the mid-1990’s which is an international group of statisticians, epidemiologists, clinical researchers and biomedical editors who collaborate to maintain the highest standards in the conduct and reporting of clinical trials (Schulz et al. 2010). The trial report claims that the study was approved by the Human Research Ethics Committee of the Universidade Federal de Sao Paulo, Brazil. However no details of the process used to gain approval or how the ethical standards were maintained during the trial have been included in the trial report.
In the trial conducted by Jorge et al. (2014) eligible subjects included women aged 40 to 70 years who were experiencing pain at described levels between 3 and 8 on a visual analog scale of 10. Initially 144 subjects were screened with only 60 women meeting the eligibility criteria based on the classification criteria of the American College of Rheumatology (Jorge et al. 2014). Using a visual analog scale is considered to be very subjective, specially when comparing groups of individuals as opposed to examining a change in pain levels of an individual participant. Other researchers prefer to use the ordering of scores instead of numbered values as such an assessment is obviously subjective (Blackwell Science 2001). These scales are of most value when looking at change within individuals, and are less valuable for comparison across a group of individuals at any given time point. Considerable care has to be exercised when interpreting such data. Many researchers prefer to use a method of interpreting results that is based on the listing of scores by rank rather than their exact values to avoid reading too much into the exact visual analog score (Blackwell Science 2001). Details of supervision by a data monitoring committee are not provided in the trial report which is a concern.
The decision to study only women limits the scope of the trial and an attempt at justification by the trial rationale is that women are more affected by osteoarthritis of the knee than men. This information was sourced from a trial by Srikanth et al. (2005) where the results highlighted sex differences in osteoarthritis prevalence and incidence, with females generally at a higher risk. A clear lack of more recent studies may compromise this justification for conducting the trial as possibly many changes in female health and fitness might have occurred in the twelve years since the trial by Srikanth. The scope of the study is further limited by the decision to only evaluate the impact of treatment on the most painful knee even though both knees may have been treated further undermines the value and credibility of the study.
The trial report of Jorge et al. (2014) in its introduction suggested there was a lack of studies precisely describing the correct application of progressive resistance exercises which also include the hip muscles however there have been several reported trials world-wide. One such trial is that of Joshua et al. (2013) which was carried out in India and reported in 2014. In this trial the experimental group were given progressive resistance exercises that strengthened the hip flexors, abductors and extensors in addition to the knee flexors and extensors (Joshua et al. 2014). Historic trial evidence also suggests that hip abductor and adductor muscle strength may be important for reducing the knee adduction moment. Lower limb strengthening exercises are an important feature of the treatment for osteoarthritis of the knee according to Bennell et al. (2007).
Jorge et al. (2014) themselves admit there were several limitations to their study which reduced both the credibility and value. In contrast to other studies such as that conducted by Joshua et al. (2013) the control group were not provided with any intervention, previous medication use was not recorded, only women were included in the study and no consequential follow up was included. This might have provided a better understanding of the impact of the progressive resistance exercise when comparing the outcomes experienced by the control group. Throughout the report there is no clear understanding offered to the reader about the interventions if any that were offered to the control group yet detailed outcomes of this group are recorded in Table 2. This prevents any meaningful comparisons being made between the beneficial impacts that the progressive resistance exercises had on the participants of the experimental group compared to those impacting the control group.This omission leaves some confusion in the mind of the reader. This criticism is supported by the findings of a review of 107 studies by Newberry et al. (2017) which concluded that the trial conducted by Jorge et al.(2013) had inherent unreliability in that blinding in the study was a concern and was declared to be high risk. Furthermore selective outcome reporting was reviewed and considered to be unclear. The review also concluded, in general, that evidence was insufficient to establish if resistance training had any beneficial long-term effects on a range of patients with osteoarthritis of the knee. Another criticism concluded that the trial did not take into account the effects of sex, disease, severity or obesity of any outcomes of resistance training (Newberry et al. 2017).
Ethical issues arising from trials such as this are covered by the Helsinki Declaration in 2008, a challenging attempt to maintain the highest quality in clinical trials. One criticism of the ethics of this trial may be that the control group participants received a lower standard of treatment than the experimental group which may have led to less favourable outcomes as detailed in the trial report (World Medical Association 2008). Funded by grants from Brazil’s leading academic research funding bodies there appears to be no conflict of interest (Science for Brazil 2017).
The clinical message contained in the conclusion of the report suggests that significant improvements in pain, function and strength were found in the experimental group beginning in the sixth week and the experimental group continued to improve throughout the study until the end (Jorge et al.2014). In contradiction, Table 2 of the report suggests that physical function, general health, emotional aspects and six minute walk test results had declined marginally in the experimental group participants 45 days from baseline during the programme.
The report claims that the progressive resistance exercise programme was effective in reducing pain and improving function yet there was no detected improvement in walking distance which is surprising given the overall recorded improvements in pain level, strength and function (Jorge et al.2014). There is however no attempt to offer an explanation for this anomaly but the reports merely recommends that further studies are needed to assess long term impact of osteoarthritis of the knee and other rheumatic conditions. The clinical value and impact of this trial on future physiotherapy application is therefore limited.
Notwithstanding the limitations and apparent contradictions highlighted in this review there is some evidence from this and other studies that progressive resistance exercise involving both the hip and knee muscles is beneficial to knee strength, mobility, pain intensity, social, emotional and mental health and well being (Jorge et al. 2014).
The report has however substantiated the authors’ submission that there is much scope for further research, especially with regard to improving walking distance amongst those females suffering osteoarthritis of the knee (Jorge et al. 2014).
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