The number of older adults in the United States living with multimorbidity—defined as the co-occurrence of at least 2 chronic conditions—has increased rapidly over the past few decades. “Visual impairment often co-occurs with other chronic conditions, such as diabetes, hypertension, and respiratory problems,” says D. Diane Zheng, PhD. “Visual impairment is among the most disabling chronic conditions and has various psychological and functional consequences, including social isolation, poor well-being, functional decline, and frailty. The combination of multiple conditions and visual impairment can have exacerbating disabling effects in older adults.”

A Deeper Look

In previous studies, research on multimorbidity has focused on a patient’s cumulative number of conditions rather than qualitative combinations of these conditions. Latent class analysis (LCA) is a statistical approach in which individuals are grouped into distinct homogeneous subgroups based on their pattern of response across several observed variables. LCA ensures that individuals within a group are more similar than those between groups.

Studies applying LCA to investigate patterns of chronic conditions and its association with visual impairment are lacking. A study published by Dr. Zheng and colleagues, published in JAMA Ophthalmology, addressed this unmet need by applying the LCA approach to identify patterns of multimorbidity with visual impairment and healthcare use. Using data from the National Health Interview Survey on nearly 388,000 U.S. adults, the authors classified patients into subgroups using LCA, with different combinations of self-reported chronic conditions. They then assessed the relationships between chronic condition grouping and the rate of self-reported visual impairment, emergency department (ED) visits, and hospitalizations in the previous 12 months.

Key Findings

The study identified 5 different classes of chronic condition patterns with main characteristics as: 1) a healthy group, 2) a hypertensive group, 3) a respiratory conditions group, 4) a heart conditions group, and 5) a severely impaired group. More than 70% of participants belonged to the healthy group, but the other 4 groups had various degrees and patterns of multimorbidity. The hypertensive group had a high prevalence of hypertension; the respiratory conditions group had a high prevalence of emphysema and asthma; and the heart disease group had a high prevalence of coronary heart disease and other cardiac diseases. The severely impaired group had a higher prevalence of most conditions when compared with the other groups.

“We found that individuals in all multimorbidity groups identified in our study had various increased risks of reporting visual impairment,” Dr. Zheng says. “Even though these groups had different patterns of disease combinations, the risk of visual impairment was heightened in all groups,” says Dr. Zheng. In an analysis adjusted for socioeconomic and health behavior factors, patients in the severely impaired group had the highest risk of visual impairment (Table). In addition to being more likely to report visual impairment, patients in all chronic condition groups used healthcare at a higher rate than the healthy group.

Of note, the study demonstrated that all multimorbidity groups had higher risks of using the ED and being hospitalized. The odds ratios for ED and hospitalization use were 9.39 and 10.80, respectively, for individuals in the severely impaired group. The study team reported that the severely impaired multimorbidity group was less educated, had lower income, and was less likely to be married. These socioeconomic factors may have contributed to their worse health.

Assessing Implications

“Our study highlights the important effect of visual impairment on a patient’s general health,” Dr. Zheng says. “The results are an important reminder that patients with multiple chronic conditions have elevated risks of visual impairment. Clinicians—including ophthalmologists and primary care physicians—would benefit from a heightened awareness of this relationship to coordinate healthcare in efforts to avert more severe consequences of multimorbidity, to prevent visual impairment, and to improve overall health.”

According to the study team, the data may be used to help identify and target high-risk multimorbidity populations that are vulnerable to health disparities and use large amounts of healthcare resources. “Our data came from national survey and were self-reported, but future research should examine if these associations remain true when measured objectively in a clinical setting,” says Dr. Zheng.