Asthma in the Elderly: Prognostic Factors

People with and without asthma were similar with respect to demographic characteristics. Physical performance was, as expected, slightly worse in the group with asthma, and in this group we also found a higher prevalence of depressed mood. No difference was found, instead, with regard to cognitive performance. Eversmokers were more prevalent in the group with asthma (56.2% vs 47.8%). We found only minimal difference between groups in the prevalence of cerebrovascular disease and diabetes, while cardiovascular diseases (including heart failure) were more prevalent in the group with asthma (Table 1).

Mortality in Asthma and Control Populations

We recorded 56 deaths in the asthma group and 180 deaths in the control group, corresponding to a risk of death at 60 months estimated using the product-limit method of 24.3% for asthmatics and 16.3% for control subjects (p < 0.01 for both log-rank and Wilcoxon tests). The corresponding survival curves are presented in Figure 1. The association of asthma with mortality was confirmed in subgroups identified by gender, age ( 75 years), and in people with low BMI, but not in people with severe comorbidity (Charlson index > 1), obesity, or in neversmokers.

Causes of death are reported in Table 2. The control group showed a much lower mortality for nonneoplastic lung disease (ICD9 codes 460-500; 5.4% vs 28.8% in the asthma group, p < 0.001), while mortality for cerebrovascular/cardiovascular diseases (ICD9 codes 400-440) was similar in the two groups. People with asthma had a slightly lower cancer mortality rate (ICD9 codes 140-240; 17.3% vs 29.8% in the control group, p = 0.163). In the multivariable analysis including potential confound-ers and terms for the interaction between diagnosis of asthma and the potential effect modifiers shown above (smoking, comorbidity, and underweight), we found that asthma was not associated with increased mortality in this population (HR, 0.77; 95% confidence interval [CI], 0.36 to 1.62).

Prognostic Factors in the Control Group

At univariable analysis, in the control group we found that demographic, clinical, and functional variables were all associated with death (Table 3). After correction for potential confounders, the association was confirmed for gender (HR for men vs women: 1.89; 95% CI, 1.28 to 2.80), age (HR for 5-year increments, 1.62; 95% CI, 1.44 to 1.83), smoking (HR, 1.52; 95% CI, 1.03 to 2.22), cardiovascular diseases (HR, 1.76; 95% CI, 1.22 to 2.54), performance on 6MWT (HR for 10% increments, 0.95; 95% CI, 0.90 to 1.00), cognitive impairment (HR, 1.93; 95% CI, 1.28 to 2.90), depressed mood (HR, 1.60; 95% CI, 1.14 to 2.25), and FEV1 (HR for 5% increments, 0.95; 95% CI, 0.91 to 0.98).

Prognostic Factors in Asthmatics

Results from univariable analysis are reported in Table 4 (second column). Age, comorbidity, underweight, physical performance, cognitive impairment, and depression were all associated with death, as were cardiovascular diseases and respiratory function.

In the multivariable model also including smoking habit (Table 4, third column), only age (HR for 5-year increments, 1.38; 95% CI, 1.07 to 1.77), smoking (HR for eversmokers vs neversmokers, 2.50; 95% CI, 1.01 to 6.18), and depressed mood (HR, 2.74; 95% CI, 1.30 to 5.76) were associated with increased mortality; while being overweight was associated with lower mortality (HR, 0.35; 95% CI, 0.13 to 0.94). Underweight, which showed the strongest association with death in the crude analysis, was still one of the strongest correlates of death after correction for potential confounders, although with wide CIs (HR, 2.21; 95% CI, 0.94 to 5.18).

This analysis was repeated in people with depression; with the limitation due to loss of power, in this subgroup gender emerged as an important risk factor, with men having a threefold increase in mortality rate compared to women (HR, 3.30; 95% CI, 1.53 to 10.35), and the association between death and being underweight was confirmed (HR, 3.14; 95% CI, 1.00 to 9.86).

Figure 1. Kaplan-Meier estimate of survival in the people with (solid line) or without (dashed line) asthma (log-rank test, p < 0.01).

Table 1—Demographic and Clinical Characteristics of Patients

Table 2—Causes of Death

Table 3—Crude and Adjusted Analysis of the Risk of Death in Control Patients Associated With Demographic, Clinical, and Respiratory Characteristics

Table 4—Crude and Adjusted Analysis of the Risk of Death in Asthmatic Patients Associated With Demographic, Clinical, and Respiratory Characteristics

Category: Asthma Facts

Tags: Asthma, depression, geriatrics, Malnutrition, mortality, Nutrition