Acetaminophen Is Ineffective for Low Back Pain

Summary and Comment |
April 2, 2015

Acetaminophen Is Ineffective for Low Back Pain

  1. Paul S. Mueller, MD, MPH, FACP

Its effectiveness for osteoarthritis-related hip and knee pain is marginal.

  1. Paul S. Mueller, MD, MPH, FACP

Acetaminophen is recommended as a first-line analgesic for low back pain and pain related to hip and knee osteoarthritis (OA), but evidence supporting this practice is weak. In this meta-analysis of data from 13 randomized trials, researchers assessed the efficacy and safety of acetaminophen (3000–4000 mg daily) versus placebo in 3500 patients with knee or hip OA and in 1800 patients with low back pain.

In patients with low back pain, acetaminophen was no more effective than placebo for pain and disability in the immediate term (≤2 weeks) or for pain, disability, and quality of life in the short term (>2 weeks–3 months). Patients with hip or knee OA who took acetaminophen had less immediate-term pain (mean difference, −3.3 mm on a 0–100 mm visual analogue scale) but not disability, and less short-term pain (mean difference, −3.7 mm) and disability (mean difference, −2.9 mm) than those who took placebo. Adverse events, treatment withdrawals, medication adherence, and use of rescue medications (e.g., naproxen) did not differ between groups, but acetaminophen users were more likely to have abnormal results on liver function tests (roughly 6% vs. 2%).

Comment

In this meta-analysis, acetaminophen was not effective in patients with low back pain. Although differences in pain and disability in patients with OA-related hip or knee pain were statistically significant, those effects were small (<4 mm difference on a 0–100 mm scale) and probably not clinically meaningful (a difference of ≥9 mm generally is considered to be clinically important). Notably, the long-term efficacy and safety of acetaminophen in patients with back pain or OA-related hip or knee pain are unknown.

Editor Disclosures at Time of Publication

  • Disclosures for Paul S. Mueller, MD, MPH, FACP at time of publication Consultant / advisory board Boston Scientific (Patient Safety Advisory Board) Leadership positions in professional societies American Osler Society (Vice President)

Citation(s):

Reader Comments (4)

CARLOS-EDUARDO GIRALDO Physician Physician, Hospital San Vicente de Paul Caldas -Colombia

This publication has an important impact in clinical practice in fact: there are a lot of points which are important to reinforce, it is important to highlight some issues : 1. Pain as a symptom is a very complex sensation, as an outcome during an investigation has the same nature, during the metodology of the study the outcome pain was well standarized but, spinal pain and osteoartritis has not the same physiopatological path which supposes a difficult point at the moment of stablish a generalization; analize both outcomes separately was, in fact, a prudent decision.
2. It is important to complement some part of the reality of many patients with chronic pain, in the specific case of the osteoartritis most of them has other comorbilities such as hypertension, diabetes or obesity and by this fact the use to consume more than 1 group of medications, this pharmacological mixture could develop elevation of the liver enzimes, in the general practice, other chemical compound specially herbal products or even food could cause measurable increments in liver enzymes. As a matter of example: Here in colombia, especially in Caldas, people has the tradition of use other substances as herbal products as a complement of the medication it is clear that the use of this products can elevate transaminases by its own nature, combined products and polipharmacy should help to explain the results. Nevertheless transaminases elevation is an important outcome to consider during the use of acetaminophen.
3. In order to conclude: It is important to consider the paper of public health and the regulation of the pharmaceutics specially in the drugs which are commercialized without prescription, paracetamol or acetaminophen is not a harmless drug in fact roberts et al in a sistematic review (Roberts, Delgado Nunes et al. Paracetamol: not as safe as we thought? A systematic literature review of observational studies. Ann Rheum Dis. 2015 Mar 2) evidences cardiovascular, gastrointestinal and renal risks; finally: the main point is to treat with respect the prescription of paracetamol.

Dale R. Hamrick MD Physician, Geriatrics, outpatient clinic

I wonder, then, about the efficacy of hydrocodone or oxycodone, as many patients look to hydrocodone/APAP or oxycodone/APAP combinations for relief of back pain. Does this in essence negate the use of these? If so, this would be very helpful to the clinician trying to sort out those truly in pain from those simply drug seeking. In addition, even those truly in pain would avoid side effects of opioid narcotics if opioids were withheld because of ineffectiveness.

Argirios Argiriou Family Medicine/General Practice, Kavala, Greece.

Do we have any other alternative (even as a placebo) for symptomatic treatment in older patients?

Elizabeth Suiter, MD Physician, Internal Medicine

Acetaminophen is not ineffective. It is no more effective than placebo which is an important distinction. As we all know placebo can be quite effective.

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