The mean age of the advanced lung cancer patient-caregiver dyads were 58.50 (SD = 10.11) years for patients and 45.47 (SD = 11.85) for caregivers. Table 1 depicts the detailed demographic and medical characteristics.
Latent profile analyses
To identify the optimal profile solution, LPA models with one to six profiles were estimated (see Table 2). The four-profile solution fitted the data significantly better than the three-profile solution; more specifically, the four-profile solution demonstrated lower values of AIC, BIC, and aBIC, higher entropy than the three-profile solution, and LMR and BLRT became significant when reaching the four-profile solution. Although the five-profile solution demonstrated lower values of AIC, BIC, and aBIC than the four-profile solution, the nonsignificant p value for LMR further confirmed that the five-profile solution did not significantly improve over the four-profile solution. Additionally, the entropy values in the four-profile solution were the highest, indicating that the four-profile solution provided fair classification accuracy.
Four profiles of dyadic QoL are presented graphically in Fig. 1. In group 1 (n=118, 38.82%), labeled as patient low-caregiver high profile, patients reported low levels of QoL, but caregivers reported a higher level of QoL than patients. Group 2 (n=68, 22.37%), labeled as patient high-caregiver high profile, was characterized by both patients and their caregivers reporting higher levels of QoL relative to the other profiles. In group 3 (n=60, 19.74%), labeled as patient high-caregiver low profile, patients reported a comparatively higher level of QoL than their caregivers, who reported low levels of QoL. Group 4 (n=58, 19.08%), labeled as patient low-caregiver low profile, was characterized by patients and their caregivers reporting lower levels of QoL compared with the other profiles.
Comparisons of demographic, medical characteristics, neuroticism, resilience, family functioning among the four profiles
The results showed that patients’ economic situation, ECOG performance status, caregivers’ age, marriage, economic situation, relationship to the patient, and the neuroticism, resilience, and family functioning of patients and their caregivers significantly differed across the four profiles (see Table 1).
Multinomial logistic regression was further conducted to explore whether the significant variables in the univariate analysis predicted profile membership (Table 3). Considering that no caregivers whose marital status was single/divorced/widowed were classified into a patient low-caregiver low profile, marriage was omitted from further analyses. The patient high-caregiver high profile was used as the reference group. Patients whose economic situation was income lesser than the expenditure (OR = 5.943; p = 0.006) were more likely to belong to the patient low-caregiver high profile compared to those with income more than the expenditure. Patients with higher scores on ECOG performance status and neuroticism were associated with increased odds of membership to the patient low-caregiver high profile and patient low-caregiver low profile. Elderly caregivers (OR = 1.067; p = 0.015) were more likely to be categorized as having a patient high-caregiver low profile. Moreover, caregivers with low resilience tended to have increased odds of belonging to the patient high-caregiver low and patient low-caregiver low profiles. Patients with high family functioning were more likely to be categorized as a patient high-caregiver low profile.
Combined Effect of patient neuroticism, resilience, family functioning and caregiver neuroticism, resilience, family functioning associated with distinct dyadic QoL profiles
As Table 4 shows, the subgroup of patient high neuroticism-caregiver low neuroticism was 3.21 times more likely to belong to the patient low-caregiver high profile compared to the dyads of patient low neuroticism-caregiver low neuroticism. The subgroup of patients and their caregivers who both had high neuroticism was 3.92 times more likely to be classified as the patient high-caregiver low profile. The subgroups of patient low neuroticism-caregiver high neuroticism, patient high neuroticism-caregiver low neuroticism, and patient high neuroticism-caregiver high neuroticism had 4.247, 9.167, and 10.869 times the likelihood of belonging to the patient low-caregiver low profile, respectively. That is, both the patients and their caregivers with a high level of neuroticism simultaneously had a higher likelihood of belonging to the patient low-caregiver low profile, compared with only one member with high neuroticism.
Furthermore, compared to patient high resilience-caregiver high resilience, the subgroup of patient low resilience-caregiver high resilience and patient low resilience-caregiver low resilience were 2.727, 7.271 times respectively more likely to belong to the patient low-caregiver high profile. In addition, the subgroup of patient high resilience-caregiver low resilience and the subgroup of patients and their caregivers with low resilience were 4.088, 8.620 times more likely to belong to the patient high-caregiver low profile, respectively. Finally, the subgroup of patient high resilience-caregiver low resilience was 4.311 times more likely to belong to the patient low-caregiver low profile, and the subgroup of patient low resilience-caregiver low resilience was 11.340 times more likely to belong to the patient low-caregiver low profile. Therefore, the dyads of both patients and their caregivers with low resilience increased their likelihood of belonging to the patient low-caregiver low profile than only one party with low resilience (OR= 11.340 vs. OR = 4.311 vs. OR = 2.223). One interesting finding is that only caregivers with lower resilience were found to be at a higher likelihood of being classified in the patient low-caregiver low profile than only patients with lower resilience (OR = 4.311, P = 0.013 vs. OR = 2.223, P = 0.173).
As for the combined effect of family functioning, the odds of both patients and their caregivers with low family functioning being classified in the patient high-caregiver low and patient low-caregiver low profiles were 5.453 and 2.944 times, respectively.