Relation between a history of glaucoma and subjective happiness: the JPHC-Next study

Introduction

Happiness is a multidimensional construct comprising both emotional and cognitive domains and has been associated with several health behaviours, such as regular exercise, not smoking, reduced alcohol intake, higher sleep quality and quantity, and healthy diet.1–4 Generally, subjective measures of health, such as self-reported health, are closely related to happiness.5–7

Several reports have evaluated the association between health condition and subjective happiness.8–11 WHO reports warned that visual impairment severely impacts quality of life (QOL) among adult populations as it contributes to social isolation, difficulty in walking, and higher risk of falls and fractures. Further, adults with visual impairment often have lower rates of workforce participation and productivity and higher rates of depression and anxiety.12

Previous studies have shown that subjective happiness is related with dry eye disease and presbyopia.13 However, the relation between subjective happiness and glaucoma remains unknown.

Vision-related QOL, defined as a person’s satisfaction with their visual ability and how their vision impacts their daily life,14 may be severely compromised in glaucoma patients,15 and a significant relationship between vision-related QOL and visual field has been reported.16 17 Here, we assessed the association between a history of glaucoma and subjective happiness in a Japanese population enrolled in the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT study).

Materials and methods

Study settings and participants

Data were derived from the JPHC-NEXT study.

The JPHC-NEXT is being conducted under a population-based cohort design in 16 municipalities of 7 prefectural areas across Japan, namely the Ninohe/Karumai area (Ninohe City and Karumai Town in Iwate Prefecture), Yokote area (Yokote City in Akita Prefecture), Saku area (Saku City, Sakuho Town, Koumi Town, Minamimaki Village, Minamiaiki Village, Kitaaiki Village and Kawakami Village in Nagano Prefecture), Chikusei area (Chikusei City in Ibaraki Prefecture), Konan/Aki area (Kagami and Noichi districts in Konan City and Aki City in Kochi Prefecture), Ozu area (Ozu City in Ehime Prefecture) and Unzen/Minamishimabara area (Unzen City and Minamishimabara City in Nagasaki Prefecture). Details of the study design have been reported previously.18 The participants were residents aged 40–74 of these seven areas.

This cohort study was initiated in 2011. The baseline survey was completed on 31 December 2016. A self-administered questionnaire was submitted to all residents of these areas, who were asked to report their lifestyle, personal medical history and sociodemographic situation. The questionnaire was mostly distributed by hand, but also by mail, between 2011 and 2016. Incomplete answers were supplemented by telephone interview. Initially, 114 054 participants consented to participate in the JPHC-NEXT study. Of these respondents, participants who had a history of any type of cancer, myocardial infarction, angina pectoris, stroke, heart failure, diabetes mellitus or depression were excluded (n=20 477). We considered that participants who frequently or regularly visited a hospital because of such conditions had a greater chance of consultation with an ophthalmologist.19 Responders without information on happiness were also excluded (n=1180). Finally, 92 397 responders were included in this study figure 1.

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Figure 1

Flow chart of data analysis.

Results

Participants in this study were characterised by a history of glaucoma in table1. The prevalence of glaucoma in this population was 1.9% (1733 participants). The average age of participants with glaucoma was 62.0±8.5 years for males (635 participants, 1.6%) and 63.6±8.1 years for females (1098 participants, 2.1%). Both men and women with a history of glaucoma were significantly older than those without (p<0.01). In addition, characteristics of the study participants stratified with age (younger group: 40–59 years, older group: 60–74 years) were shown in online supplemental table 1.

Table 2 shows ORs for happiness by history of glaucoma. The odds of unhappiness in participants with a history of glaucoma were significantly higher than in those without among male participants (OR 1.26; 95% CI 1.05 to 1.51). Female participants with a history of glaucoma were subjectively unhappier than those without, but the difference was not significant (OR 1.05; 95% CI 0.90 to 1.23).

In the analysis stratified by age, younger participants aged 40–59 years with a history of glaucoma showed more severe subjective unhappiness (OR 1.40; 95% CI 1.04 to 1.88) than those aged 60–74 years (OR 1.20; 95% CI 0.96 to 1.51) among male participants. In contrast, no significant relationship between subjective unhappiness and history of glaucoma was seen among female participants in either age group (online supplemental table 2).

Discussion

In this study on the relationship of a history of glaucoma and subjective happiness, we found that participants with a history of glaucoma tended to have more subjective unhappiness than those without this history. In a subgroup analysis stratified by age, among participants with a history of glaucoma, the most robust association with unhappiness was seen in males in the younger group (40–59 years). These findings suggest that younger glaucoma patients may have serious concerns about environmental changes, especially employment, due to progressive visual field impairment.

A nationwide survey of newly certified visually impaired individuals in Japan between 2015 and 2016 showed that glaucoma was the most common disease (28.6%) among all causes of blindness.22 Here, we found that the OR of unhappiness in participants with a history of glaucoma was high. Although diagnosis and treatment of glaucoma relatively early in its course can help slow the progression rate and minimise functional impairment,23 a retrospective population-based cohort study by Malihi et al estimated that the probability of glaucoma-related blindness in one or both eyes over 20 years’ follow-up was 13.5% (95% CI 8.8% to 17.9%).24 Visual field loss was associated with impaired daily functioning, such as diminished enjoyment of reading and watching television, and a higher risk of incident falling.25 Further, Zhang et al reported that glaucoma patients were subject to being unaware of the progression of their glaucoma, as glaucoma tends to be associated with a younger age at onset and more complex treatment, including both medications and surgeries.26 In addition, glaucoma surgery was not associated with a significant improvement in Hospital Anxiety and Depression Scale score before and after surgery.26

An Australian review indicated that only one-third of the population aged over 65 years with visual impairment was employed, compared with those over this age without visual impairment.27 Therefore, opportunities for employment may be a concern in glaucoma patients, particularly in the elderly population. Additionally, this review calculated that the total cost of glaucoma, including health system costs, indirect costs and costs of loss of well-being, would increase from $AUD 1.9 billion in 2005 to $AUD4.3 billion in 2025.27

In this study, we found that a history of glaucoma increased ORs for unhappiness in men only and that no significant association with subjective happiness was seen in women. In contrast, an institution-based cross-sectional study conducted in Ethiopia28 showed that female is a risk factor for depression in glaucoma. Considering the social context that the main wage earner in a wage worker’s family in Japan is likely to be male,29 the sex difference in this study may be due to the fact that men are often dependent on their income and that if they have visual impairment, they may have difficulty in working. A multiethnic Asian population study showed that even mild visual impairment is associated with unemployment and underemployment.30 Shimazaki et al reported that experience of involuntary informal employment was associated with higher risk of mental health problems, especially among men.31

In our male younger group (age 40–59) participants with a glaucoma history, the most prevalent category of household income was the highest category, namely ≥$60 000/year. In contrast, among the male older group (age 60–74) with a glaucoma history, the most prevalent category was the lowest category, at <$30 000/year (online supplemental table 1). The prevalence of subjective happiness by each household income category is shown in online supplemental table 3. The results showed that 38% of those with the lowest household income (<$30 000/year) were classified as unhappy and only 17% as happy. Conversely, 38% of those with the highest household income (≥$60 000/year) were classified as happy and 20% as unhappy. Therefore, we cannot conclude that the higher the income, the unhappier the participants in this study.

A previous cohort study conducted in Taiwan showed that glaucoma patients had a significantly higher risk of depression (adjusted HR=1.71), and raised the possibility that a lack of financial or emotional support may predispose glaucoma patients to depression.32 In Japan, a multicentre prospective case–control study by Mabuchi et al reported a prevalence of anxiety among Japanese patients with primary open-angle glaucoma of 13.0%, and a prevalence of depression of 10.9%.33 Given that symptoms of depression are associated with happiness,34 we excluded participants with a history of depression from the main analysis and also conducted a subanalysis which included those with a history of depression (online supplemental table 4). The prevalence of depression among those with a history of glaucoma is almost double that of those without (men: 3.1% vs 1.3%, women: 3.2% vs 1.7%, respectively). Our results are consistent with a previous report showing that younger age was a risk factor for anxiety and depression in glaucoma patients,35 suggesting that younger glaucoma patients may be anxious about changes in their employment environment, and reduced income due to progressive visual field impairment.

The higher prevalence of glaucoma in women than men in this study might be associated with the difference between sexes in the percentage of participants receiving medical advice in Japan.36 The Japanese Ministry of Health, Labour and Welfare conducted a patient survey of eligible persons using medical facilities throughout Japan and found that women were more likely to consult a doctor than men.37

The strengths of this study are its large participant population and wide enrolment of participants across Japan, and its minimisation of the effects of potential confounding factors in examining the relation between unhappiness and glaucoma.

Several limitations of this study also warrant mention. First, given that the presence of glaucoma was self-reported and information from ophthalmological examinations was lacking, the diagnosis may not be accurate. Additionally, because the current questionnaire did not ask about the severity of glaucoma, this variable cannot be evaluated. While the prevalence of glaucoma in Japanese aged over 40 years is estimated at 5.0%,38 the self-reported prevalence in this study was low, at 1.9%. Assessment by self-report might therefore carry the risk of underascertainment of cases, and postsurgical participants may also have answered that they had a history of this disease. Nevertheless, a previous large nationwide population study selected a self-reported history of ophthalmological disease for analysis.39

Second, participants who reported that they feel happy may not report histories of disease. Confirmation of these results will require further study using more accurate diagnoses, obtained using medical records or evaluation via ophthalmic examination. Furthermore, as noted above, although the breadwinner in Japanese families is often male, the questionnaire does not enquire about this variable and it cannot be assumed from the answers. Finally, although we excluded participants in the dataset with depression, the potential risk of residual confounding due to depression remains.

In conclusion, this study shows that the presence of glaucoma is associated with subjective unhappiness.