Most current guidelines advocate that persons over the age of 50 years be screened with FOBT every one to two years or with colonoscopy every 10 years (5
). Although disparities in CRC screening recommendation have been documented, their nature and role were unclear. Our study provides evidence for age-related disparities in physician delivery of CRC screening recommendation to screen-eligible, average-risk persons. The interaction between age group and depression was the most important determinant of physicians’ delivery of a colonoscopy recommendation. Although a greater proportion of patients in the younger age group were depressed, only depression in the older age group was associated with lack of delivery of a recommendation for colonoscopy. Several reasons for this observation can be postulated. Primary care patients who present with chronic depression may offset physicians’ screening offerings to address the more pressing issue of depression. Because depression in younger patients did not seem to influence delivery of CRC screening recommendation, older age may be a key factor driving physicians’ decision to not recommend colonoscopy screening. Physicians may be taking into account the arduous preparation and invasiveness of the procedure, which may be more difficult at advanced ages. Alternatively, primary care patients who present with a new, unexplained episode of depression may prompt physicians to recommend screening because a new depressive episode may be an underlying symptom of occult malignancies such as CRC (22
). The age by depression interaction also indicated that physicians recommended FOBT 69% less often to older depressed patients versus younger nondepressed patients. Similarly, because FOBT is self-administered, providers may perceive that older depressed patients will find preparation and performance of the examination to be a daunting task and will, therefore, be less compliant.
The role of comorbidity was explored as a factor that might influence physician delivery of screening recommendations. We expected that, because comorbidity generally increases with increasing age, older patients would have more comorbidity and would be less likely to receive a screening recommendation regardless of the modality. However, there was no association between an age by comorbidity interaction and delivery of screening recommendation for any modality. In contrast, patients with comorbidity, regardless of age, were marginally less likely to receive an FOBT recommendation. The clinical importance of this finding lies in the fact that physicians often consider quality versus quantity of life when offering screening for a malignancy (24
) and may perceive that patients with comorbidity would not derive sufficient benefit from screening. Furthermore, providers may not offer FOBT to patients with comorbid conditions because FOBT may be more difficult to complete than examinations that are administered by health care professionals. Collectively, these results suggest that comorbidity operates independently of ageism as a determinant of physician delivery of FOBT recommendation.
Additionally, we observed an association between marital status and physician delivery of colonoscopy recommendation. Although this association remained marginally significant in the presence of other patient characteristics, the clinical implication is noteworthy. Physicians may perceive that married compared with unmarried patients have greater social support, are more stable, and may, therefore, be more compliant with screening. This finding suggests that marital status may be an important factor that influences CRC screening recommendations. Another explanation is that marital status may promote screen-seeking behaviour; married patients may ask their physicians to recommend screening because their spouse underwent screening.
Surprisingly, no significant association was found between patient characteristics and delivery of FOBT versus colonoscopy recommendation. Possibly, the lack of identifiable predictors between these two modalities stems from the fact that CRC screening guidelines are inconsistent across organizations, leaving physicians to base their modality choice on personal belief and preference. Physicians may adhere to one screening modality and thus may choose to not give any screening recommendation as opposed to recommending an alternative screening modality. Therefore, factors such as patient characteristics that could potentially influence recommendations would not be observed between different screening modalities.
There are several potential study limitations worth discussing. The first is the lack of documentation regarding the nature of the index visit. Primary care physicians are more likely to discuss CRC screening during visits for routine physicals than for follow-ups (25
), which may be more common among older individuals with comorbidity. To address this possibility, we assessed the age-comorbidity relationship between screen-eligible and nonscreen-eligible patients. We found that older patients had significantly more comorbidity than younger ones in the screen-eligible patients only. Therefore, it is plausible that more of the older, unwell patients were visiting the clinics for follow-ups. However, the lack of association between the age-comorbidity interaction and delivery of a screening recommendation indicates that older patients with comorbidity were as likely to receive a screening recommendation as any other patient. This suggests that, in our study population, the nature of the medical visit did not influence delivery of the screening recommendation. Nevertheless, physicians may have recommended screening regardless of the nature of the medical visit owing to a Hawthorn effect. Another limitation is that because ascertainment of patient screen-eligibility was by self-report, patients may have misunderstood the test description and failed to report a personal history of screening. Finally, differences between patient’s and physician’s modality of choice were not documented; physicians may have under-reported screening delivery if the patient immediately refused to comply with the screening modality recommended.