A randomized clinical trial of manual therapy and physiotherapy for persistent back and neck complaints: subgroup analysis and relationship between outcome measures.

OBJECTIVE: To study the efficacy of manual therapy and physiotherapy in subgroups of patients with persistent back and neck complaints. The second objective was to determine the correlation between three important outcome measures used in this trial.

DESIGN: Randomized clinical trial (subgroup analysis).

SETTING: Primary health care in the Netherlands.

PATIENTS: Two hundred fifty-six patients with nonspecific back and neck complaints of at least 6 wk duration who had not received physiotherapy or manual therapy in the past 2 yr.

INTERVENTIONS: At the discretion of the manual therapists, physiotherapists and general practitioners. Physiotherapy consisted of exercises, massage and physical therapy (heat, electrotherapy, ultrasound, shortwave diathermy). Manual therapy consisted of manipulation and mobilization of the spine. Treatment by the general practitioner consisted of drugs (e.g., analgesics), advice about posture, home exercises and (bed)rest. Placebo treatment consisted of detuned shortwave diathermy (10 min) and detuned ultrasound (10 min).

MAIN OUTCOME MEASURES: Changes in severity of the main complaint and limitation of physical functioning measured on 10-point scales by a blinded research assistant and global perceived effect measured on a 6-point scale by the patients.

RESULTS: Improvement in the main complaint was larger with manual therapy (4.3) than with physiotherapy (2.5) for patients with chronic conditions (duration complaint of 1 yr or longer). Also, improvement in the main complaint was larger with manual therapy (5.5) than with physiotherapy (4.0) for patients younger than 40 yr (both were measured after 12-mo follow-up). Labeling of patients by the treating manual therapists as "suitable" or "not suitable" for treatment with manual therapy did not predict differences in outcomes. Generally, there was a moderate to strong correlation between the three outcome measures, although a considerable number of patients gave a relatively low score for perceived benefit, while the research assistant gave a high improvement score for the main complaint and physical functioning.

CONCLUSIONS: The subgroup analysis suggests better results of manual therapy compared to physiotherapy in chronic patients (duration of present complaints of 1 yr or longer) and in patients younger than 40 yr old). Differences for other subgroups were less clear. The explorative findings of these subgroup analyses have to be investigated in future research.