Randomised clinical trials (RCTs) that evaluated the effectiveness of spinal manipulation in people of any age as a treatment for asthma, compared with any control group, were eligible for inclusion. To be included, trials had to include a clinical outcome (lung function, symptoms, medication usage).
In the included trials, the interventions were high velocity, low amplitude directional thrust to dysfunctional joints of the spine by a chiropractor. Control groups received sham manipulation. Treatment ranged from one to three months. Participants were treated for mild, moderate or chronic childhood asthma. Outcomes reported were lung function tests, symptom scores, bronchodilator use, bronchial reactivity, peak expiratory flow, patient related symptoms and medication use.
The author did not state how many reviewers selected studies for inclusion.