Excess use of general practitioners by obese adults: Does health-related quality of life account for the association?

Abstract

As general practitioners (GP) are seeing, and are likely to continue to see, increasing numbers of obese patients in their practices, it is relevant to know with which needs these patients enter general practice. The present study aims to determine whether besides physical comorbidities, health-related quality of life (HRQOL) accounts for associations of obesity with GP use. In a general population survey in Augsburg, Germany (KORA-Survey S4 1999/2001), anthropometric body mass (BMI in kg/(m²)), physical comorbidities, HRQOL (the 12-item Short Form; SF-12), and visits to GP were assessed, and analyzed by logistic and zero-truncated negative binomial regressions (two-part model). Gender, age, socio-economic status, marital status, health insurance, and place of residence were adjusted for. The sample consisted of N = 942 residents aged 25 – 74, who had been randomly sampled from 17 cluster-sampled communities, and were either normal-weight, overweight, moderately obese, or severely obese. The moderately obese group had higher odds than the normal-weight to report any GP use; however, while being predictive, neither physical comorbidity nor HRQOL mediated this. In contrast, with regard to number of GP visits among users, the severely obese group (BMI ≥ 35) reported significantly more visits than the normal-weight group, and both physical comorbidity and physical (but not mental) HRQOL accounted for this. In conclusion, physical comorbidity and HRQOL mediate excess use of GP by severely obese users in terms of number of visits. Thus, for this group, subjective physical health seems to be important besides physical comorbidities, suggesting for general practice to focus both on evaluated and perceived needs of these patients.

Keywords:

• General practitioners
• health services utilization
• health-related quality of life
• obesity
• severe obesity

Notes

1. In weighting the index for disease severities, the standardized beta coefficients provided in Groll et al. (2005; Table 3) were used, except for degenerative disc disease. For the latter, we extrapolated a weight from that study reported by Groll et al. (2005), which included this condition (.33). Also, our index neither included obesity (as our focal explanatory variable) nor neurological disease (such as multiple sclerosis or Parkinson's), depression, anxiety or panic disorders, visual impairment (such as cataracts, glaucoma, macular degeneration), and hearing impairment (very hard of hearing, even with hearing aids), since they were not available to us. This reduction from originally 18 to 12 conditions has been judged by the FCI's originator as nonetheless rendering an index with acceptable validity (Dianne Groll, personal communication, 1 April 2006). However, as our adaptation excludes all mental diseases, for conceptual precision we use the designation “physical FCI” throughout this paper. Besides, while authors debate the usefulness of considering disease severities in indexing comorbidities (Groll et al., 2005), we use the weighted version due to more evidentiary associations than the unweighted form with health care use in previous analyses (von Lengerke & John, 2006; von Lengerke & John, 2007). Finally, in general terms, the selection of the FCI as basis for indexing comorbidities using our data basically rests on two rationales. First, an alternative index employed by Werner, Reitmeir, and John (2005) has been validated only as a dichotomous index (i.e., any vs. no morbidity). Second, the FCI, when compared to other indices allowing the analysis of multiple comorbidities of different severity (e.g., the Charlson index; Charlson, Pompei, Ales, & MacKenzie, 1987), is the one most relatable to the assessment of medical histories in the present survey.