A Critique Of Hill Et Al. (2016) Study On The Effectiveness Of High And Low Dose Fish Oil For Treatment Of Knee Osteoarthritis

Write a appraisal in an essay style paper."effectiveness of the high-dose fish oil and low-dose."

Section 1: What was the study about?
What was the research question?
Who was eligible to participate in the study?;
How many groups were there and what did each group receive?
What outcomes (dependent variables) were measured and when?

Section 2: What is the risk of bias in the study?

How did the researchers control allocation bias?Were participants randomly assigned to groups and how as this doneWas the allocation sequence concealed?
How did the researchers control performance bias?Were participants blind?Was blinding successful?Were the people providing the intervention blind?
How did the researchers control detection bias? Were the outcome assessors blind?
How did the researchers control attrition bias? What was the withdrawal rate (loss to follow up) in each group over time? Did they use intention to treat analysis?

In this essay, the article by Hill et al. (2016) is criticallyevaluated by using the CASP tool. The authors tried to compare the effects of an anti-inflammatory dose of fish oil with lower dose of the fish oil. In this study, a randomized controlled trial method was used and almost 202 participants were allocated randomly in two groups that was high-dose group and low dose group. The researcher also tried to establish a relationship between the cessation of cartilage degradation among the Osteoarthritis (OA) patients after consuming the high dose fish oil. In previous studies it was observed that use of fish oil among the patients of rheumatoid arthritis was effective in preventing structural degradation(Di Giuseppe et al., 2014)and researcher expected that it would also improve the condition of the OA patients as the structural degradation was common among the two type of arthritis (Pap & Korb-Pap, 2015).

Research question:

The study of Hill et al. (2016) is based on the examination of the effectiveness of the high-dose fish oil in comparison with the dose of low-dose supplementations in treatment of the knee osteoarthritis (OA) in older persons.

The research question of this study is as below-

• Is high dose fish-oil is better than low-dose supplementation in the treatment of knee OA?
• Can high-dose fish oil stop the structural degradation in OA?

Eligibility criteria:

In this study, researcher selected the populations who had pre-defined knee OA and the determination of the disease was done by following the ACR criteria. The subject population must have the age of 40 years or more. In addition, the visual analogue scale of knee pain was also used. In a scale 0-100mm, the persons who had the knee pain score of >20mm, was counted as an eligible subject for the study. However, during the sample selection, researcher followed a few exclusion criteria for the sample population. The exclusion criteria for this study were as below-

• People who have dementia or disability to sign the consent form
• Woman in pregnancy condition or in the lactation period
• Planned knee replacement surgery previously
• Use of high-dose fish oil for more than 6 months
• Persons who have contraindications to MRI scan
• People with severe radiographic knee OA index that is grade 3 radiographic joint space narrowing as per the guideline of Osteoarthritis Research Society International Atlas.

People having any one or more criteria was excluded from the study. Moreover, before starting the actual study, a 4 week trial period was performed and in this process, similarly flavored oil was used to detect the persons allergic to the oil. Subjects, who were intolerance to the oil were eliminated from the actual study.

Sample:

In the final study, there were two groups and the treatment was different for the each group. The first group received high dose of fish oil and the second group was treated with low dose of fish-oil. The high dose oil composed of EPA 18% and DHA 12%. This mixture was supplying 4.5 gm of DHA+ EPA mixture per day (Hill et al., 2016). In the low-fish oil of the second group, a ratio of 1:9 of low dose fish oil and sunola oil were maintained. This mixture was supplying 0.45 gm DHA+ EPA per day and that was equivalent to 1.5 standard 1gm fish oil capsule. However, both the group had dose of 15 ml of fish oil every day. All the participants were provided Paracetamol (500 mg) and they were instructed that they could have the drug upto 8/day(Hill et al., 2016).

Eligibility Criteria

Primary outcome:

The primary outcomes for this study were knee specific pain scales according to the WesternOntario and McMaster Universities Arthritis (WOMAC) index at different time that was at 3 months, 6 months, 12 months and 24 months. In addition to this, the changes in the cartilage volume was also measured by using MRI technique at the 24 months. After that, the secondary outcomes that were quality of life, NSAIDs and analgesic use, WOMAC function, change in the safety score and BML score, were measured. The WOMAC knee pain index was measured on a 10-point numerical scale. The assessor instrument for measuring the quality of life was validated in both OA patients and general populations. The MRI scans of the study were executed at baseline and 2 years with 1.5 T.

Risk of bias:

In order to control the allocation bias in the double blinded Randomized Controlled Study (RCT)(Burls, 2014), the researcher used the computer technology for allocation of the participants to the groups. A random allocation sequence was used during the allocation process of the subject population and further recruitment was done at a pharmacy. The participants were randomly assigned to the high dose and low dose treatment group after surviving in the tolerance test of flavored oil that was performed before the final randomization. The allocation sequence was concealed throughout the whole study and both the participants and assessor were unaware about the allocation sequence(Hill et al., 2016).

Performance bias:

A performance bias refers to an adverse outcome that happened during or after exposure of the drug. This adverse event may occur due to the exposure to the intervention. This bias is occurred from a systematic difference that is different from intervention between the control and experimental group (Burls, 2014). In this study by Hill et al. (2016), the researcher had nullified the chances of allocation bias by performing a study of 4 week duration. In this pre-randomization study, the researcher used a citrus-flavored sunola oil that had similarity in fragrance with the actual fish oil which would be used in actual study. The persons who were unable to tolerate the smell of the oil, excluded from the study. In this all the participants were kept blind throughout the process in a successful way. After the study, it was observed that 52% of total sample population were in dilemma regarding their allocation that was they did not know in which group they were allocated during the study. Remaining participants anticipated that they knew their allocation group. In that case, it was observed that, only 57% answered correctly and that suggested that the researcher maintained the blindness well. All the staff involved in the care process of the participants were kept in blind situationand along with this the MRI technicians were also did not know any information regarding the experiment.

Sample

Detection bias:

In this study, researcher used one trained reader during assessment of the individual cartilage plate volumes to remove detection bias. During this time researcher resampled the according to cubic and bilinear interpolation. The trained reader was completely unaware of the process. During the BML assessment, the reader had no information regarding clinical data and treatment allocation (Hill et al., 2016).

Attrition bias and withdrawal rate:

During the study, almost 54 samples that is almost 26.7% had not completed the study and in different stages they discontinued the study intervention practices. However, the researcher continued the study for two years. In spite of discontinuation, the overall study had the follow-up percentage of 84. All the participants were assessed at 12 months and 24 months(Hill et al., 2016). However, at the baseline, the participants of each group were matched except in the male-female population ratio. The withdrawal rate of the participants was higher in the high dose group than that of the low dose group. It was observed that, the withdrawal rate was 35% among the patients having high dose while the participants of the low dose group had the withdrawal rate of 20%. After the final allocation to the group, each group initially had same number of subject (n= 101). Within the 1 year period, 32 participants discontinued the process from the high dose group and the number of withdrawal from the low dose group was 17. From the time period of 1year to 2 year, 3 participants from the high dose group discontinued the process and the same number of participants discontinued the process from the low dose group (Hill et al., 2016). The withdrawal cases in the high dose group happened within 3 months of starting the study whereas the withdrawal cases of the low dose groups mainly happened after 7.5 months of the initiation of the study. Moreover, it was observed that, after randomization, female participants were mostly found in high dose group than that of the low dose oil group. In high dose oil group, the percentage of female participants were 59% and in the low dose group, this percentage was 40 having the p value of < 0.01(Hill et al., 2016).

Conclusion

In conclusion, it was observed from the study that the low dose group had lower pain score than that of the high dose group at 18 and 24 months and low dose group also had the better functional limitation score at 24 months. Along with this, no significant change was observed between the groups regarding the cartilage volume from baseline to 24 months. It can be said the author failed to establish the effectiveness of high dose over the low dose with statistically significant result.

References:

Burls, A. (2014). What is critical appraisal?. Hayward Medical Communications.

Di Giuseppe, D., Crippa, A., Orsini, N., & Wolk, A. (2014). Fish consumption and risk of rheumatoid arthritis: a dose-response meta-analysis. Arthritis research & therapy, 16(5), 446.

Hill, C. L., March, L. M., Aitken, D., Lester, S. E., Battersby, R., Hynes, K., ... & Jones, G. (2016). Fish oil in knee osteoarthritis: a randomised clinical trial of low dose versus high dose. Annals of the rheumatic diseases, 75(1), 23-29.

Pap, T., & Korb-Pap, A. (2015). Cartilage damage in osteoarthritis and rheumatoid arthritis—two unequal siblings. Nature Reviews Rheumatology, 11(10), 606.