Panel findings and recommendations:
- Acetaminophen is reasonably safe and is acceptable for treating patients with low back problems.
(Strength of Evidence
- Nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, are acceptable for treating patients with low back problems.
(Strength of Evidence = B.
- NSAIDs have a number of potential side effects. The most frequent complication is gastrointestinal irritation. The decision to use these medications can be guided by comorbidity, side effects, cost, and patient and provider preference.
(Strength of Evidence
- Phenylbutazone is not recommended, based on an increased risk for bone marrow suppression.
(Strength of Evidence = C
Acetaminophen, a nonnarcotic analgesic, has commonly been regarded as having an analgesic effect, but little or no known anti-inflammatory mechanism. The therapeutic objective for its use in low back problems is pain relief.
NSAIDs are a class of medications, including aspirin, ibuprofen, indomethacin, phenylbutazone, and a variety of other drugs. They have anti-inflammatory and analgesic properties as well as being prostaglandin inhibitors. The therapeutic objective of NSAIDs in treating low back problems is to decrease pain, presumably by reducing inflammation and promoting healing.
Acetaminophen and NSAIDs
Acetaminophen and NSAIDs
Of 50 articles screened for this topic, 4 RCTs met the review criteria for adequate evidence about efficacy.85
Other articles did not meet the criteria, but contained information used by the panel. 93
Evidence on Efficacy.
The four RCTs that met review criteria for this topic were all double-blind studies comparing NSAIDs with a placebo in treating patients with low back problems. No studies were found that compared acetaminophen to placebo in treatment of patients with low back pain.
Two studies compared a single NSAID to a placebo: Amlie, Weber, and Holme90
evaluated piroxicam. Postacchini, Facchini, and Palieri85
evaluated diclofenac. The study by Berry, Bloom, Hamilton, et al.92
had three treatment groups evaluating either one of two NSAIDs (diflunisal or naproxen sodium) or a placebo. The study by Basmajian91
compared four treatment groups receiving an NSAID alone (diflunisal), a muscle relaxant alone (cyclobenzaprine), the two in combination, or a placebo.
Three of the studies evaluated patients with low back symptoms of less than 3 months' duration.85
Berry, Bloom, Hamilton, et al.92
evaluated patients with chronic low back pain.
Three studies found NSAIDs superior to a placebo for pain relief in the short term: from 1 week to 2 months of symptom duration.85
The remaining study found no significant difference between NSAID and placebo in terms of pain improvement scores.91
Although there were no RCTs comparing acetaminophen to placebo for patients with low back pain, one nonplacebo-controlled RCT found an NSAID (diflunisal) superior to paracetamol (which is similar to acetaminophen) in producing pain relief for patients with chronic low back pain.97
In addition, the literature on acetaminophen does show it to be more effective than placebo in studies of patients with nonback-related pain.98
Several RCTs comparing efficacy of different NSAIDs in the same study have found no NSAID to be consistently more effective than the others.96,101
However, these studies also suggest that individual patients report better pain relief from some NSAIDs compared with others. For this reason, Brooks and Day93
suggest that patients change to a different NSAID if no relief is reported after a 2-week trial.
Potential Harms and Costs
. The risks from the use of acetaminophen at usual doses are low.95
However, high doses of acetaminophen can lead to liver damage, and massive single doses sometimes lead to fatal hepatic necrosis. Compared with NSAIDs, acetaminophen has a minimal effect on platelets and few gastrointestinal side effects since it is not a mucosal irritant. Acetaminophen is inexpensive. The expense of treatment with NSAIDs varies greatly, depending on the medication used and the length of treatment.
Potential complications of NSAIDs have been extensively studied. 93
These include gastritis and other gastrointestinal complaints, including bleeding in 20 to 30 percent of those patients with active peptic ulcer problems. The degree of gastrointestinal side effects from NSAIDs appears to be dose related, but side effects can occur with one tablet. Ingestion of NSAIDs with meals or in combination with antacids has not been proven effective in reducing these gastrointestinal side effects. However, one medication (misoprostol), when taken with NSAIDs, has been shown to reduce NSAID-induced gastric erosion and the risk for gastroduodenal ulcers. 99
NSAIDs interfere with platelet adhesion and renal sodium metabolism. Their use in patients with a bleeding diathesis is considered contraindicated. They can be used in the presence of hypertension, renal disease, and edematous states, but only if great caution is exercised.93
For these reasons, some experts caution that routine blood tests (such as CBC and serum chemistry screen) be done before treatment for older patients or those with vascular disease. These tests are also recommended if there is any suspicion of complications for those patients on prolonged NSAID therapy.95
Phenylbutazone has been associated with bone marrow suppression (aplastic anemia and agranulocytosis). Indomethacin has a higher reported incidence of gastrointestinal side effects than other NSAIDs. Otherwise, there is no significant demonstrated difference between remaining NSAID preparations in terms of the prevalence or severity of complications.95
Summary of Findings
. There is fair to good evidence that NSAIDs are effective for reducing pain in patients with acute low back problems. Although no studies were found comparing acetaminophen to placebo in patients with back pain, there is evidence that acetaminophen is comparable in efficacy toNSAIDs for treating back problems and with fewer side effects. In studies of patients with nonback pain, no consistent difference in symptom relief has been demonstrated between acetaminophen and any available NSAID (including aspirin). Both NSAIDs and acetaminophen have been found to be generally adequate to achieve pain relief.
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