Abstract
Purpose:
To investigate the burden of visual impairment and comorbid fatigue in terms of impact on daily life, by estimating societal costs (direct medical costs and indirect non–health care costs) accrued by these conditions.
Methods:
This cost-of-illness study was performed from a societal perspective. Cross-sectional data of visually impaired adults and normally sighted adults were collected through structured telephone interviews and online surveys, respectively. Primary outcomes were fatigue severity (FAS), impact of fatigue on daily life (MFIS), and total societal costs. Cost differences between participants with and without vision loss, and between participants with and without fatigue, were examined by (adjusted) multivariate regression analyses, including bootstrapped confidence intervals.
Results:
Severe fatigue (FAS ≥ 22) and high fatigue impact (MFIS ≥ 38) was present in 57% and 40% of participants with vision loss (n = 247), respectively, compared to 22% (adjusted odds ratio [OR] 4.6; 95% confidence interval [CI] [2.7, 7.6]) and 11% (adjusted OR 4.8; 95% CI [2.7, 8.7]) in those with normal sight (n = 233). A significant interaction was found between visual impairment and high fatigue impact for total societal costs (€449; 95% CI [33, 1017]). High fatigue impact was associated with significantly increased societal costs for participants with visual impairment (mean difference €461; 95% CI [126, 797]), but this effect was not observed for participants with normal sight (€12; 95% CI [−527, 550]).
Conclusions:
Visual impairment is associated with an increased prevalence of high fatigue impact that largely determines the economic burden of visual impairment. The substantial costs of visual impairment and comorbid fatigue emphasize the need for patient-centered interventions aimed at decreasing its impact.
In 2015, the number of visually impaired people worldwide was estimated to be 253 million.
1 The worldwide societal costs of visual impairment have been estimated at $3 trillion in 2010,
2 partially explained by direct medical costs related to health care utilization,
3,4 and indirect costs characterized by loss in work participation.
5 The prevalence and economic burden of visual impairment are projected to increase by 20% in 2020 owing to demographic growth and aging of populations in Western society.
2
Fatigue is an important problem for patients with irreversible visual impairment,
6 and is often referred to as an overwhelming sense of tiredness associated with impaired physical and/or cognitive functioning.
7 Patients with visual impairment described fatigue as an indirect result of vision loss through/by a high cognitive load, the effort that is necessary for visual perception, difficulties with light intensity, and negative cognitions related to negative thoughts.
8 Vision loss seems to be related to increased symptoms of fatigue. Mojon-Azzi et al.
9 report a positive association between self-reported vision impairment and severity of fatigue. Also, in comparison with matched controls without ocular disease
10–12 and with regard to vision problems in patients with chronic conditions,
13,14 this relationship has been supported. However, no studies have investigated the prevalence of fatigue in persons with visual impairment.
The consequences of vision-related fatigue have been described by a qualitative approach, including difficulties with emotional functioning, the ability to carry out roles, societal participation, cognitive functioning, and maintaining daily activities.
8,15 Therefore, fatigue may increase the individual burden of visual impairment, but this has not been previously studied. This notion is supported by research in depression; Robinson et al.
16 report greater use of medication and health care utilization for patients with clinical levels of fatigue, resulting in an increased economic burden for society. Fatigue also generates societal costs due to the negative implications for employment and work productivity.
17,18 Studies in patients with cancer and multiple sclerosis, for example, have identified fatigue as the key symptom influencing work capacity and preventing return to work.
19,20
A greater understanding of the costs of vision-related fatigue will help inform health care decision-makers in setting up and prioritizing health care policies and interventions for people with visual impairment. Cost-of-illness studies are an essential measure in health care that allow for an evaluation of the economic burden of a disease on society as a whole.
21 Our study aimed (1) to determine the individual burden of fatigue in visually impaired adults compared with normally sighted adults, in terms of severity, impact on daily functioning, need for recovery after work, and prevalence; and (2) to estimate the societal burden of visual impairment and comorbid fatigue in terms of direct health care costs and indirect non–health care costs.
FAS scores (mean difference 5.0; 95% CI [4.0, 6.0]) and MFIS scores (mean difference 11.8; 95% CI [9.0, 14.5]) were significantly higher for participants with vision loss than for normally sighted participants. These differences (FAS: mean difference 4.3; 95% CI [3.8, 4.8] and MFIS: mean difference 11.1; 95% CI [7.6, 14.5]) remained significant after controlling for potential confounders. Severe fatigue (FAS ≥ 22) and high fatigue impact (MFIS ≥ 38) were present in 57% and 40% of participants with vision loss, respectively, which was significantly higher compared to 22% and 11% in those with normal sight (odds ratio [OR] 4.7; 95% CI [3.1, 7.0] and OR 5.3; 95% CI [3.3, 8.6], respectively), also after adjustment for confounders (severe fatigue: OR 4.6; 95% CI [2.7, 7.6] and high fatigue impact: OR 4.8; 95% CI [2.7, 8.7]).
Supported by “ZonMw Inzicht,” the Netherlands Organizations for Health Research and Development – InSight Society (Grant No. 60-0063598146), The Hague, The Netherlands. The findings of the cost of illness study presented here are part of a larger research project on fatigue among adults with visual impairment.
Disclosure: W. Schakel, None; H.P.A. van der Aa, None; C. Bode, None; C.T.J. Hulshof, None; G.H.M.B. van Rens, None; R.M.A. van Nispen, None