Parenteral Treatment of Episodic Tension-Type Headache: A Systematic Review

Danielle Weinman, MD; Olivia Nicastro, NP; Olabiyi Akala, MD; BenjaminW. Friedman, MD


Headache. 2014;54(2):260-268. 

In This Article



We performed a systematic review of the medical literature to identify the efficacy and adverse event profile of parenteral treatments for acute tension-type headache when compared to placebo or active controls. The protocol was reviewed by the Albert Einstein College of Medicine IRB and determined to be exempt from further ethical review.

Inclusion and Exclusion Criteria

We identified randomized trials in which one parenteral treatment was compared to another active comparator or to placebo for the treatment of acute tension-type headache in adults. Parenteral was defined as intravenous, intramuscular, or subcutaneous administration. We only included studies that distinguished tension-type headache from other primary headache disorders, such as migraine, using criteria that were consistent with the International Classification of Headache Disorders.[2] We included studies only if there was an assessment of the acute efficacy of the medication, which we defined as an assessment of pain within 6 hours of the investigational medication administration. As NSAIDs, acetaminophen, and salicylates are standard therapy for tension-type headache, we did not include studies that only compared one of these agents with placebo or with another one of these agents. Studies were also excluded if the majority of patients were less than 18 years old.

Search Strategy

Using a search strategy detailed in Table 1, we searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, and Google Scholar (articles). Databases were searched from inception through August, 2012. We performed searches of electronically available conference proceedings from the following scientific meetings: Society for Academic Emergency Medicine, American Headache Society, and the American Pain Society. We searched to identify any recently completed or unpublished studies. We also searched reference lists of included studies to identify additional studies.

Study Selection

One author screened all abstracts returned by the search for potential eligibility. Two authors then independently screened abstracts to determine if an article was appropriate. Discrepancies were resolved through a review of the full article and discussion, though in each of these cases, a third reviewer who was part of the discussion broke the deadlock.

Outcomes of Interest

The primary outcome for this review was a measure of efficacy 1 hour after medication administration. If 1 hour outcomes were not reported, we preferentially used outcomes measured 30 to 59 minutes after investigational medication administration. If these too were not available, we used any endpoint recorded before 361 minutes had elapsed, with a preference for those outcomes measured closest to 1 hour. We were most interested in reporting the outcome number needed to treat (NNT), as this has clear clinical significance. NNT was based on a dichotomous measure of pain relief, using the following hierarchy of outcomes: headache freedom, >50% reduction in pain score, improvement of pain level from severe or moderate to mild or none, or requirement of rescue medication. NNT was calculated by taking the inverse of the absolute risk reduction reported in the original studies. Absent dichotomous outcomes, we abstracted continuous measures of efficacy. Adverse medication events are reported as number needed to harm (NNH). Other outcomes, such as recurrence of headache after initial successful treatment and repeat visit to health-care provider are reported when available.

Data Abstraction

Data abstraction was performed by two authors. Disagreements were resolved by a third author.

Assessment of Bias

We assessed the internal validity of trials using the Cochrane Collaboration risk of bias tool. Rather than relying on a checklist or score, this instrument provides a summary assessment of the risk of internal bias in a study. Risk of bias is graded as low, unclear, or high. The summary assessment of bias is determined based on assessments of the risk of selection, performance, detection, attrition, and reporting bias, as well as an assessment of other potential biases.


Because of substantial heterogeneity among study designs, medications used, and outcomes assessed, we decided that combining data and reporting summary statistics would not represent the original data meaningfully. The results of individual studies are presented using NNT and NNH with 95% CI when dichotomous outcomes were reported. When continuous outcomes were reported, we describe each group's percent improvement, defined as improvement in pain/baseline pain.