Article
Determining the Role of Stress in the Progression of AMD
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Perceived Stress Scale worked well in assessing stress levels of AMD patients.
For many patients, age-related macular degeneration (AMD) is highly distressing. AMD patients have reported that their condition causes a level of emotional distress that is comparable to that reported by melanoma and bone marrow transplant patients.
Some of the main reported psychological effects of AMD include anxiety, depression, and stress. Moreover, the possibility of permanent vision loss is not the only stressor AMD patients face. The inability to engage in pleasurable and valued activities or even basic tasks of daily living also can cause the negative feelings, and so does the prospect of having to receive regular intravitreal injections.
However, the association between AMD and perceived stress is not as well studied as that between AMD and depression. In addition, the extent to which stress may accelerate AMD and vision loss is unclear.
The Perceived Stress Scale (PSS) was developed to assess the stressfulness of life events and to determine how much stress influences the progression of various diseases. This well-validated, reliable, and well-established scale has been used to measure stress in many diverse populations across a broad range of health conditions in numerous published studies. Furthermore, in those studies, age and gender appeared to have a minimal effect on PSS scores.
Moreover, PSS scores have been found to correlate with the number of stressful life events as well as health outcomes. In addition, the PSS is able to predict objective biological markers of stress and general markers of inflammation, including the level of C-reactive protein.
Recently, a team from the Ohio State University Department of Ophthalmology and College of Optometry in Columbus, Ohio, attempted to validate the PSS in AMD patients by using Rasch analysis. This analytic method assesses a psychometric scale’s performance and ability to distinguish between patients with different levels of perceived stress, among its other properties.
The team recruited 137 study participants who visited the retina service of the Ohio State University Department of Ophthalmology for treatment or regular follow-up observation of AMD. The mean age of the participants was 82 ± 9 years, and 54% of the participants were women.
In the study group, the median visual acuity of the better-seeing eye according to Early Treatment of Diabetic Retinopathy Study (ETDRS) criteria was 65 letters, or by Snellen chart, 20/50 (range, 20/800—20/15). Nearly half (47%) of the participants were scheduled to receive an intravitreal injection of an anti-vascular endothelial growth factor agent on the day of the study visit.
The team determined that nine of the ten questions on the PSS worked well in assessing the stress levels of the AMD patients studied. In addition, they found that those nine items could distinguish between patients with higher levels of perceived stress and those with lower levels.
For some items, responses differed by age and visual acuity. Nevertheless, no significant correlation was found between better-eye visual acuity and the amount of perceived stress experienced by PSS responders (r = −0.04; P = 0.06).
According to the study team, further research aimed at determining whether stress accelerates AMD depends on solid validation of the PSS in AMD patients.
In addition, the team noted that PSS scores have been associated with increased levels of pro-inflammatory cytokines. “Because AMD is an inflammatory disease, we are studying the link between inflammation, stress, and AMD treatment outcomes,” reported team leader Bradley Dougherty (pictured above), OD, PhD, in a press release from the American Academy of Optometry.
If the team determines that stress worsens AMD outcomes substantially, the use of stress-reduction approaches such as mindfulness-based techniques may help to improve outcomes in AMD patients as it has in others with various health conditions, the investigators noted.
Their study report, “Measurement of perceived stress in age-related macular degeneration,” appears in the March, 2017, issue of Optometry and Vision Science.
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