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Paracetamol, aspirin and caffeine for tension type headache

Clinical bottom line:

Caffeine containing compounds are effective for the acute treatment of tension type headache. The number-needed-to-treat for a patient to achieve at least 50% pain relief at four hours was about 5 for both aspirin 500 mg/paracetamol 500 mg/caffeine 130 mg and paracetamol 1000 mg/caffeine 130 mg.


Systematic review

Migliardi JR, Armellino JJ, Friedman M, Gillings DB, Beaver WT. Caffeine as an analgesic adjuvant in tension headache. Clin Pharmacol Ther 1994; 56:576-86.

Date review completed: June 1994 (re-analysed Dec 2000)

Number of trials included: 6 randomised controlled trials

Number of patients: 2555 Control group: placebo and active (paracetamol)

Main outcomes: Headache pain intensity difference (PID) and total pain relief (TOTPAR), number-needed-to-treat (NNT)

Inclusion criteria were were randomised, double-blind, placebo controlled trials of moderate to severe headache treated with paracetamol/aspirin/caffeine or paracetamol/caffeine; adult patients; IHS diagnosis tension-type headache.

Authors calculated mean SPID scores and TOTPAR for each trial separately as well as pooled. We have used these data to produce relative benefits and numbers-needed-to-treat for the number of patients achieving at least 50% pain relief with caffeine containing compounds compared with placebo.

Findings

Four trials compared paracetamol 500 mg + aspirin 500 mg + caffeine 130 mg, paracetamol 1000 mg and placebo in patients with moderate to severe episodic tension-type headache. In all four trials, the paracetamol/aspirin/caffeine combination provided significantly better pain relief than paracetamol and placebo at 4 hours. On average 57% (range 53% to 63%) of patients had at least 50% pain relief over four hours with placebo, compared with 76% (range 72% to 80%) with the combination analgesic.

Over four hours, paracetamol/aspirin/caffeine had a relative benefit of 1.3 (1.2 to 1.4) and a number-needed-to-treat of 5.2 (4.2 to 6.7) for at least 50% pain relief.

Two trials compared paracetamol 1000 mg + caffeine 130 mg, paracetamol 1000 mg and placebo in patients with moderate to severe episodic tension-type headache.

Over four hours paracetamol 1000 mg + caffeine 130 mg had a relative benefit of 1.3 (1.2 to 1.5) and a number-needed-to-treat of 5.6 (4.1 to 8.5) for at least 50% pain relief.

Combination analgesics were statistically superior both to placebo and to paracetamol (acetaminophen) alone.

Adverse effects

Significantly more patients experienced adverse effects with caffeine containing compounds than placebo. These were mainly dizziness and nervousness.

Comment

What is interesting about these six studies, which are described in great detail, is the very high rate of success with placebo. Half the patients had at least 50% pain relief without any active analgesic. This is a high figure.

Firstly, high placebo rates reduce the sensitivity of clinical trials to distinguish any treatment response, underining the fact that combination analgesics are effective. Second, it demonstrates that for many people the headaches will go away without treatment.