Purpose: The purpose of this study was to determine if the Outcome Questionnaire 45.2 (OQ-45) can be used in the treatment of obesity to predict participant dropout and initial treatment success, in terms of weight loss (Lambert et. al, 2002a). The OQ-45 has been used with success to predict dropout from psychotherapy in clinical populations. It was hypothesized that higher pretreatment OQ-45 scores would be associated with less program completion and less weight loss by the end of treatment.

Method: The study employed a non-experimental time series design. Seventy-eight participants were recruited from the three local obesity treatment programs, which varied in length from 8 to 12 weeks. Participants were asked to complete the OQ-45 and report their current weight at the beginning of each treatment session.

Analysis: Of the 76 participants with valid pretreatment OQ-45 scores, 27.6% had scores at or above the cutoff value of 64, indicating psychological distress. Overall, one-third (32.9%) of participants completed their treatment program by attending at least half of the eight sessions. Participants with high OQ-45 cutoff scores were significantly less likely to complete the treatment program compared to those with low scores (14.3% vs. 40.0% respectively, p = 0.03). Pretreatment OQ-45 cutoff scores did not predict either attendance at the second treatment session or weight loss success in terms of pounds lost. However, even when controlling for gender, ethnicity, and treatment site, high OQ-45 scores predicted program dropout (OR = 4.41 [95% Cl = 1.07 - 18.10] p = .039), but not weight loss failure.

Implications for Preventive Care: Obesity has proven to be especially difficult to treat, in part due to the high attrition rates from treatment programs. This study demonstrates the potential use of the OQ-45 in obesity treatment to predict participants who are more likely to drop out of treatment. This may allow health care professionals to focus attention on those at increased risk for attrition, thereby improving treatment outcomes.


School of Public Health

First Advisor

Edward Fujimoto

Second Advisor

Helen Hopp Marshak

Third Advisor

David Vermeersch

Degree Name

Doctor of Public Health (DrPH)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Obesity -- prevention and control; Outcome Assessment (Health Care); Treatment Outcome.



Page Count

ix; 77

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives