J Periodontol • April 2002 Relationship of Clinical Depression to Periodontal Treatment Outcome John R. Elter,* B. Alex White, † Bradley N. Gaynes, ‡ and James D. Bader § 441 Background: Depression has been associated with periodontal disease; however, its relationship to periodontal treatment out- come (PTO) has not been investigated. Methods: Data were obtained by chart abstraction and com- puter databases on 1,299 health maintenance organization (HMO) patients aged 30 to 64 who had concurrent medical, dental, and pharmacy benefits, and who had an initial peri- odontal examination during 1996, 1997, or 1998. Depression (yes/no) was the main independent variable and was deter- mined by presence of any diagnosis code for depression on the patient record. PTO was determined by the difference in percent of sites with probing depth (PD) ≥5 mm between the initial and 1-year post-treatment periodontal exams. Sub-median peri- odontal treatment outcome (SMPTO) was defined as a reduc- tion in fewer than the median percent of sites (7.33%) with PD ≥5 mm. Information on sociodemographics, periodontal ther- apy, calculus and plaque, number of remaining teeth, smoking, antidepressant medications, and diabetes were collected. Results: A total of 697 patients had a periodontal exam at both baseline and follow-up. Of these, 12.2% had depression. In a multivariable logistic model, depression (odds ratio [OR] 2.16, 95% confidence interval [CI] 1.12 to 4.16) and 4-month recall treatment (OR 2.34, CI 1.46 to 3.75) were associated with SMPTO, while percent of sites at baseline with PD ≥5 mm (OR 0.93, CI 0.91 to 0.94), number of remaining teeth at baseline (OR 0.94, CI 0.89 to 0.99), and number of teeth lost during the study period (OR 0.75, CI 0.58 to 0.96) were negatively asso- ciated. Periodontal surgery, age, gender, smoking, plaque, cal- culus, diabetes, and antidepressant medication were not signif- icant in the model. Conclusion: Clinical depression may have a negative effect on periodontal treatment outcome in this group model HMO population. J Periodontol 2002;73:441-449. KEY WORDS Depression; outcome assessment; periodontal disease/ therapy. * Department of Dental Ecology and Center for Oral and Systemic Diseases, School of Dentistry, UNC Chapel Hill, Chapel Hill, NC. † Center for Health Research, Kaiser Permanente NorthWest Division, Portland, OR. ‡ Department of Psychiatry, School of Medicine, UNC Chapel Hill. § School of Dentistry and Cecil B. Sheps Center for Health Services Research, UNC Chapel Hill. C linical depression has been linked to more extensive and more severe periodontal disease, 1,2 as well as more rapid periodontal disease progres- sion in longitudinal studies. 3,4 While the mechanism for such an association is poorly understood, it is thought to be through a negative effect on the immune system, 5-10 (Fig. 1, pathway 1) coupled with poor behavioral compliance with oral hygiene and treatment recommenda- tions 1,11 as well as increased smoking and other risk behaviors 12 (Fig. 1, path- way 2). While an impaired immune response in persons with depression has not been consistently demonstrated, one study has shown that young adult sub- jects with major depression had more cir- culating leukocytes and granulocytes, fewer CD56+ cells, and less NK cell activ- ity. 6 Another study found no mean dif- ferences between depressed cases and matched controls in mitogen-induced lymphocyte proliferation, lymphocyte subsets, and natural killer cell activity. 5 Differences between these studies may relate to the patient subgroups investi- gated. Clinical depression has been impli- cated in large alterations in cellular immu- nity 8,10 and in humoral immunity. 9 These hypothesized reductions in immune re- sponse may serve to facilitate increased colonization by pathogenic bacteria, which may lead to breakdown of the peri- odontal attachment mechanism. Alter- natively, depression may also mediate more rapid periodontal disease progres- sion through neglect of oral hygiene, changes in diet, increase in smoking and other risk behaviors, bruxism, alterations in gingival circulation, changes in saliva,