Use of a single global assessment to reduce missing data in a clinical trial with follow-up at one year.
We conducted a randomized controlled trial (ISRCTN96537534) to assess the effects of acupuncture on migraine and chronic tension headache. Patients (n=401) completed a diary of headache severity four times a day for 4 weeks at baseline, immediately following a 3-month treatment period and 1 year after randomization. During the trial, it appeared that dropout might be higher than expected. We therefore obtained a rapid global assessment of headache from participants to aid imputation of missing data. Patients were contacted by telephone and asked to rate current and baseline headache on a 0-10 scale. Use of global assessment reduced the number of patients from whom we obtained no follow-up headache data from 69 (17%) to 24 (6%). Analysis of patients who provided both a diary and a global assessment demonstrated excellent properties of global assessment, with very similar results to the full diary. We therefore used the global assessment to help impute missing 1-year diary scores. Rapid global assessment can be easily implemented in any trial and aids imputation of missing data, though it should not be used instead of more intensive methods of assessment. Further research might usefully examine the value of global assessment for imputation of missing data in a variety of different settings.
Vickers
Andrew J
AJ
Integrative Medicine Service, Biostatistics Service, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA. vickersa@mskcc.org
McCarney
Rob
R
D026881:Acupuncture; D003625:Data Collection / Q000379:methods; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D008499:Medical Records; D008881:Migraine Disorders / Q000628:therapy*; D010352:Patient Dropouts; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D018570:Risk Assessment; D013689:Telephone; D018781:Tension-Type Headache / Q000628:therapy