Table 2. Incidence density rates and hazard ratio for chronic fatigue syndrome according to dry eye syndrome status stratified by demographic factors and comorbidity.
| Dry eye syndrome | Compared to no DES cohort | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No | Yes | Crude HR (95% CI) | Adjusted HR (95% CI) | |||||||
| Variables | Event | Person-year | IR | Event | Person-year | IR | ||||
| Overall | 54 | 17986.70 | 3.00 | 28 | 4489.88 | 6.24 | 2.08 | (1.32–3.28)** | 1.61 | (1.01–2.58)* |
| Gender | ||||||||||
| Female | 47 | 13400.12 | 3.51 | 22 | 3362.67 | 6.54 | 1.87 | (1.13–3.10)* | 1.49 | (0.88–2.51) |
| Male | 7 | 4586.58 | 1.53 | 6 | 1127.21 | 5.32 | 3.48 | (1.17–10.36)* | 2.38 | (0.75–7.54) |
| Age, years | ||||||||||
| 20–64 | 33 | 12475.10 | 2.65 | 22 | 3098.20 | 7.10 | 2.69 | (1.57–4.61)*** | 1.96 | (1.12–3.42)* |
| ≥ 65 | 21 | 5511.60 | 3.81 | 6 | 1391.68 | 4.31 | 1.14 | (0.46–2.83) | 1.05 | (0.42–2.66) |
| Comorbidity‡ | ||||||||||
| No | 17 | 8750.30 | 1.94 | 3 | 1329.56 | 2.26 | 1.16 | (0.34–3.97) | 1.22 | (0.36–4.18) |
| Yes | 37 | 9236.40 | 4.01 | 25 | 3160.32 | 7.91 | 1.97 | (1.19–3.28)** | 1.98 | (1.19–3.29)** |
Abbreviation: DES, dry eye syndrome; IR, incidence density rates, per 1,000 person-years; HR, hazard ratio; CI, confidence interval.
Adjusted HR: mutually adjusted for age, gender, and comorbidity in Cox proportional hazards regression.
‡ Patients with any one of cancers, systemic lupus erythematosus, rheumatoid arthritis, Sjogren syndrome, depression, anxiety, sleep disturbance, irritable bowel syndrome, and fibromyalgia were listed as the comorbidity group.
* p < 0.05, ** p < 0.01, *** p < 0.001.