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Author:  gmohan [ 04 Apr 2015 01:25 ]

Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials
BMJ 2015; 350 doi: (Published 31 March 2015)

To investigate the efficacy and safety of paracetamol (acetaminophen) in the management of spinal pain and osteoarthritis of the hip or knee.

Design Systematic review and meta-analysis.

Data extraction
Two independent reviewers extracted data on pain, disability, and quality of life. Secondary outcomes were adverse effects, patient adherence, and use of rescue medication. Pain and disability scores were converted to a scale of 0 (no pain or disability) to 100 (worst possible pain or disability). We calculated weighted mean differences or risk ratios and 95% confidence intervals using a random effects .

12 reports (13 randomised trials) were included. There was “high quality” evidence that paracetamol is ineffective for reducing pain intensity (weighted mean difference −0.5, 95% confidence interval −2.9 to 1.9) and disability (0.4, −1.7 to 2.5) or improving quality of life (0.4, −0.9 to 1.7) in the short term in people with low back pain.
For hip or knee osteoarthritis there was “high quality” evidence that paracetamol provides a significant, although not clinically important, effect on pain (−3.7, −5.5 to −1.9) and disability (−2.9, −4.9 to −0.9) in the short term.
The number of patients reporting any adverse event (risk ratio 1.0, 95% confidence interval 0.9 to 1.1), any serious adverse event (1.2, 0.7 to 2.1), or withdrawn from the study because of adverse events (1.2, 0.9 to 1.5) was similar in the paracetamol and placebo groups. Patient adherence to treatment (1.0, 0.9 to 1.1) and use of rescue medication (0.7, 0.4 to 1.3) was also similar between groups. “High quality” evidence showed that patients taking paracetamol are nearly four times more likely to have abnormal results on liver function tests (3.8, 1.9 to 7.4), but the clinical importance of this effect is uncertain.

Paracetamol is ineffective in the treatment of low back pain and provides minimal short term benefit for people with osteoarthritis.
These results support the reconsideration of recommendations to use paracetamol for patients with low back pain and osteoarthritis of the hip or knee in clinical practice guidelines.

What is already known on this topic

Clinical guidelines recommend paracetamol as first line analgesic drug for both spinal pain (neck and low back pain) and osteoarthritis of the hip and knee
The evidence base supporting these recommendations has recently been called into question

What this study adds

High quality evidence suggests that paracetamol is ineffective in reducing pain and disability or improving quality of life in patients with low back pain
There is high quality evidence that paracetamol offers a small but not clinically important benefit for pain and disability reduction in patients with hip or knee osteoarthritis

Though high quality evidence shows that patients taking paracetamol are nearly four times more likely to have abnormal results on liver function tests compared with those taking oral placebo, the clinical relevance of this is unclear.

G Mohan.

Author:  Badri [ 10 Apr 2015 01:04 ]


To me this article appears a bit controversial. Paracetamol is prescribed all over the world and millions have been taking it. NHS choices clearly states - "paracetamol is a safe and effective painkiller when taken correctly". Your report indicates that the study was compiled by collecting results from 12 independent reports. Where the patients checked for abnormal liver function before paracetamol was prescribed. Do we know where these reports were collected from and whether the authors collected papers that suited their study.

First of all, we all know that maximum dose paracetamol taken for a prolonged period of time can cause liver damage. Acute liver failure does occur in patients attempting suicide with overdose of the drug. Secondly we also know that a small dose of paracetamol taken for a brief period for acute back pain of sudden onset or when prescribed for patients with osteoarthritis already on NSAI with sudden exacerbation of pain respond well to the drug. I have prescribed it for many patients with advise to take it for a brief period (in addition to their NSAI) with excellent results.

Please do tell us a bit more about this paper as it is likely to cause unnecessary panic among the patients.


Author:  gmohan [ 14 Apr 2015 23:17 ]


New research shows that paracetamol is ineffective in reducing pain, disability or improving quality of life for patients who suffer from low back pain or osteoarthritis of the hip or knee, and its use may affect the liver.

The study published today in The BMJ provides new evidence that paracetamol is no better at treating low back pain than a placebo and its effect on osteoarthritis of the hip or knee is too small to be clinically worthwhile.

Lead author, Gustavo Machado of The George Institute and the University of Sydney says the results of this systematic review provide cause to review guidelines that endorse paracetamol for back pain and osteoarthritis.

“World-wide, paracetamol is the most widely used over-the counter medicine for musculoskeletal conditions so it is important to reconsider treatment recommendations given this new evidence,” says Mr Machado.

“Use of paracetamol for low back pain and osteoarthritis was also shown to be associated with higher risk of liver toxicity in patients,” he says. “Patients were nearly four times more likely to have abnormal results on liver function tests compared to those taking placebo pills.”

Low back pain is the leading cause of disability worldwide, and osteoarthritis of the hip or knee is the 11th highest contributor to global disability. In Australia, back pain and osteoarthritis account for $8.4 billion in health care costs per year.

Senior author Associate Professor Manuela Ferreira of the George Institute for Global Health and the University of Sydney says there is increasing evidence questioning conventional treatments for back pain and other musculoskeletal conditions.

“For example, last year The George Institute showed that paracetamol does not speed recovery or reduce pain for acute low back pain,” says Associate Professor Ferreira.

“This latest research, the most comprehensive systematic review of its kind, reaffirms this with an even larger, global patient base, and has for the first time also established that the effects of paracetamol for knee and hip osteoarthritis are too small to be of clinical importance.”

“We are also seeing increasing evidence examining early medical imaging for low back pain, which can cost up to $220 million a year in Australia, that shows that this procedure isn’t always necessary,” she says. “We urgently need to take stock of the evidence for common musculoskeletal conditions, a largely under-recognised health priority, and make sure people are receiving appropriate care.”

Osteoarthritis expert, Professor David Hunter of the University of Sydney says this new research demonstrates the importance of reviewing paracetamol guidelines for treating osteoarthritis.

“A separate study published* recently has shown that paracetamol can be associated with an increasing incidence of mortality and increased risk of cardiovascular, gastrointestinal and renal disease in the general adult population,” says Professor Hunter.

“Clinicians should carefully weigh benefits and harms when making treatment decisions. Paracetamol is not efficacious and potentially harmful. In this context we cannot justify its continued use for these prevalent diseases.”

Paracetamol is currently recommended by most international clinical guidelines as a first line treatment for low back pain and osteoarthritis.

Other treatments known to be effective for patients with low back pain include advice and education programs, physical therapies such as spinal manipulation and exercise as well as psychological therapies such as cognitive behavioural therapy.

Land or water-based aerobic exercise, strengthening exercise, weight management and oral or topical anti-inflammatory medicines have been shown to provide benefit for patients with lower limb osteoarthritis.

I shall add my Critical Appraisal of the study soon, and answer the questions raised by Badri

G Mohan.

Author:  gmohan [ 19 Apr 2015 02:49 ]

Where did the story come from?

The study was carried out by researchers from the University of Sydney, St Vincent’s Hospital and University of New South Wales and Concord Hospital in Sydney. It was funded by the National Health and Medical Research Council.

The study was published in the peer-reviewed British Medical Journal (BMJ) .
The UK media reported the story accurately but did not explain any of the limitations of the study.

What kind of research was this?

This was a systematic review of all RCTs assessing the effectiveness of paracetamol for back pain and osteoarthritis of the hip or knee compared to placebo.
The researchers also performed a meta-analysis. This is a statistical technique that combines the results of the RCTs to give an overall measure of effectiveness.
Pooling the results of multiple studies can help to give a better estimate of effectiveness, which is sometimes not seen in the individual studies, for example if they are too small.

This type of research is good at summarising all the research on a question and calculating an overall treatment effect, but relies on the quality and availability of the RCTs.

Paracetamol is currently recommended as the first line for pain relief for back pain and osteoarthritis of the hip and knee in clinical guidelines. The researchers wanted to assess whether this recommendation is backed up by the evidence.

What did the research involve?

A systematic review and meta-analysis was performed to identify and pool all RCTs that have assessed paracetamol compared to placebo for back pain and osteoarthritis of the hip and knee.
The following medical databases were searched for RCTs published up until December 2014: Medline, Embase, AMED, CINAHL, Web of Science, LILACS, International Pharmaceutical Abstracts, and Cochrane Central Register of Controlled Trials. A search was also made for unpublished studies, and authors were contacted for further information where required.

Three reviewers selected all relevant RCTs that reported on any of the following outcomes:
pain intensity
disability status
quality of life
Trials were excluded where a specific serious cause of the back pain had been identified, such as a tumour or infection, if they looked at post-operative pain and studies of people with rheumatoid arthritis.

The quality of each RCT was assessed using the standardised approach called a "risk of bias" assessment. The strength of the body of evidence as a whole was summarised using the internationally recognised GRADE approach (The Grading of Recommendations Assessment, Development and Evaluation).
A meta-analysis was then performed to pool the results of trials in people with the different conditions using appropriate statistical methods. This included an analysis of whether the RCTs were similar enough to be combined. The researchers also performed "secondary exploratory analysis", which looks at the effect various different factors may have had in biasing the results.

What were the basic results?

The systematic review included 13 moderate- to high-quality RCTs and 12 of them in the meta-analysis:
three trials investigated short-term use of paracetamol for lower back pain (including 1,825 people)
10 trials assessed paracetamol compared to placebo for osteoarthritis of the knee or hip (including 3,541 people)
no trials were found for neck pain

No significant difference was found between paracetamol and placebo in the short term control of lower back pain in terms of:
pain intensity
quality of life

Paracetamol slightly improved pain and disability from osteoarthritis of the hip or knee compared to placebo.

People experienced a similarly small number of side effects when taking paracetamol or placebo.
All patients had pre and post Liver function tests.
However, people taking paracetamol were [/color]four times more likely to have abnormal liver function tests than those taking placebo.

How did the researchers interpret the results?

The researchers concluded that "paracetamol is ineffective in the treatment of lower back pain and provides minimal short term benefit for people with osteoarthritis". They call for "reconsideration of recommendations to use paracetamol for patients with lower back pain and osteoarthritis of the hip or knee in clinical practice guidelines".


This systematic review and meta-analysis suggests paracetamol may not be effective for some people with lower back pain and of limited help to people with osteoarthritis of the hip and knee.

Strengths of the study include:
the systematic review only contained the "gold standard" type of trials – RCTs
existing published RCTs comparing paracetamol with a placebo were likely to have been identified, as a large number of databases were searched from the beginning of their records up to December 2014.
[color=#4000FF]There were also two independent reviewers, which reduces the risk of any slipping through the net

they also searched for unpublished studies, reducing the risk of publication bias in their results (trials are less likely to be published if their results do not show a clear benefit)
the quality of evidence was appropriately assessed
However, as noted above, this type of research is reliant on the availability of relevant RCTs.

So while the review itself was well-conducted, the actual body of new evidence found about lower back pain was small.
Some people will find paracetamol helps relieve the pain with relatively few side effects compared to other types of pain killers. The UK guideline recommends paracetamol as a first line pain relief drug for lower back pain that has lasted for at least six weeks, along with other measures such as staying active. They recommend that if this does not provide adequate pain relief, then an NSAID should be offered.

UK is currently updating its guidance on lower back pain and will take the results of this review into account.

UK guidance also recommends paracetamol as a first line pain relief drug for osteoarthritis, however it does note that an evidence review suggested paracetamol may not be as effective for these people as originally thought. They are going to be reviewing this guidance (a draft is expected in 2016), and may revise their recommendations at that point, but for now have kept their existing guidance.

Note for patients
If you are finding that any prescribed treatment doesn’t seem to be working then you shouldn’t suddenly stop taking it (unless advised to). You do have the option of contacting your doctor in charge of your care to discuss alternative drug (as well as non-drug) options.

G Mohan.

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