Perceived Time Availability for Self-Care and Quality of Life in Patients with Major Depressive Disorder: A Cross-Sectional Study in Ho Chi Minh City, Vietnam

Abstract

Background: Major depressive disorder (MDD) severely impairs quality of life (QoL), yet contextual constraints such as perceived time availability for self-care remain underexplored in low- and middle-income countries. This study evaluated multidimensional QoL and identified its independent correlates among outpatients with MDD in Ho Chi Minh City, Vietnam. Methods: A cross-sectional study was conducted among 290 outpatients with MDD on stable antidepressant therapy. Subjective QoL was measured using the WHOQOL-BREF, and depressive severity using the Quick Inventory of Depressive Symptomatology–Self Report (QIDS-SR16). Four domain-specific multivariable linear regression models applying robust standard errors were constructed. Results: Physical (45.2 ± 12.1) and Psychological (46.3 ± 12.7) QoL were most severely compromised. Depressive symptom severity was the strongest independent negative predictor across all four domains (p < 0.001). Lower perceived economic status predicted poorer psychological, social, and environmental QoL. Notably, severe perceived time constraint (“No time” for self-care) independently predicted lower Environmental QoL (β = −10.21, SE = 4.53, p = 0.025) after controlling for economic status and depression severity. Outpatients diagnosed within one year reported lower physical, psychological, and environmental QoL compared to those with 1–5 years of illness. Conclusions: Depressive severity is the most consistent correlate of QoL in Vietnamese outpatients with MDD, whereas perceived time availability for self-care exerts a domain-specific association with Environmental QoL. Comprehensive outpatient care should integrate symptom reduction with lifestyle-oriented guidance and psychosocial support.

1. Introduction

Major depressive disorder (MDD) is a major contributor to the global burden of disease and non-fatal disability [1,2]. Characterized by persistent low mood, anhedonia, cognitive deficits, and altered self-perception, MDD causes profound impairments in daily functioning and overall well-being [1,3]. Traditionally, psychiatric interventions have focused primarily on acute symptomatic reduction or clinical remission [1,2]. However, contemporary psychiatric literature increasingly emphasizes that symptomatic relief alone does not automatically restore social roles, personal satisfaction, or full functional capacity [2,4]. Consequently, the assessment of Quality of life (QoL)—defined by the World Health Organization (WHO) as an individual’s subjective perception of their position in life within the context of their culture, value systems, goals, and expectations [1,5]—has emerged as an essential primary outcome measure for evaluating comprehensive therapeutic success in depression management [2,4].

Prior empirical studies in diverse clinical settings demonstrate that individuals with MDD experience substantial impairments across all four QoL domains: physical health, psychological health, social relationships, and environment [2,4]. The degree of QoL reduction observed in MDD is frequently more severe than that reported in chronic physical conditions such as diabetes mellitus, hypertension, or end-stage renal disease [4]. While depressive symptom severity has consistently been established as the strongest negative predictor of QoL [2,6,7], clinical severity alone accounts for only a portion of the variance in QoL outcomes [1,2,4]. This indicates that QoL is a complex construct influenced by socio-demographic factors, financial stability, personal autonomy, and environmental living conditions [8,9,10]. In low- and middle-income countries (LMICs), mental healthcare systems remain predominantly centered on psychopharmacological management, often neglecting broader socio-contextual factors that shape patients’ daily lives and recovery [9].

In rapidly urbanizing environments such as Ho Chi Minh City, Vietnam, industrialization and socioeconomic transitions place considerable time demands on individuals [11]. Outpatients living with MDD often navigate demanding occupational schedules, domestic caregiving obligations, and restricted discretionary time—structural barriers that may limit their capacity to engage in health-promoting self-care practices and restorative activities [12]. In the present study, the construct of “perceived time availability for self-care” represents an individual’s subjective appraisal of whether they possess adequate time to engage in personal health, physical rest, and psychological recovery. Furthermore, within a chronic illness framework, prolonged disease duration may trigger psychological adaptation or “response shifts,” wherein patients recalibrate their personal expectations, develop adaptive coping mechanisms, and stabilize their subjective QoL over time [13,14]. However, the independent associations between perceived time availability for self-care, illness duration, and specific QoL domains among outpatients with MDD in Vietnam remain unexplored.

To address these empirical gaps, this study was conducted with two specific objectives: (1) to evaluate the level of subjective QoL across four distinct domains (Physical, Psychological, Social Relationships, and Environment) using the WHOQOL-BREF instrument among outpatients with MDD in Ho Chi Minh City, Vietnam, and (2) to examine the independent associations between depressive symptom severity, subjective economic status, perceived time availability for self-care, illness duration, and domain-specific QoL scores using multivariable linear regression models, controlling for relevant sociodemographic and clinical covariates.

2. Materials and Methods

2.1. Study Design and Setting

A cross-sectional study was conducted from September to December 2024 at the Psychiatric Clinic of the University Medical Center, a tertiary-level hospital in Ho Chi Minh City. Ethical approval was granted by the institutional review board, and all participating patients provided written informed consent prior to enrollment.

2.2. Participants and Eligibility Criteria

Participants were recruited consecutively during routine follow-up visits. Eligibility criteria included: age ≥ 18 years; a DSM-5-TR diagnosis of major depressive disorder (MDD) confirmed by board-certified psychiatrists; stable antidepressant treatment for ≥8 weeks to ensure assessment during the chronic/stabilized phase of illness. Exclusion criteria were acute psychotic symptoms, severe cognitive impairment, pregnancy, or comorbid severe psychiatric disorders (e.g., bipolar disorder, schizophrenia) that could confound QoL evaluations specific to MDD. These criteria align with methodologies used in previous chronic-phase MDD studies [8].

2.3. Sample Size

The sample size calculation was initial based on a single population mean formula for QoL outcome measures: $\mathrm{n}⩾{\left({\displaystyle \frac{{\mathrm{Z}}_{(1-\mathsf{\alpha }/2)}\mathsf{\sigma }}{\mathrm{d}}}\right)}^2$, where Z_(1-α/2) = 1.96 corresponding to a 95% confidence level (α = 0.05), d = 2.0 denotes the acceptable margin of error, and σ = 16.4 represents the estimated standard deviation of the WHOQOL-BREF Psychological Health domain score derived from the depression subgroup (mean score 47.1 ± 16.4) in a previous psychiatric outpatient study in Singapore [15]. This yielded an initial sample size requirement of n ≥ 259, which increased to N = 285 after allowing for a 10% non-response rate. Ultimately, 290 eligible outpatients completed the assessment and were included in the final analysis. Furthermore, to evaluate whether this sample size provided sufficient statistical power for the multivariable linear regression models comprising 17 predictor parameters, Green’s rule of thumb (N ≥ 50 + 8m, where m is the number of predictors) was applied [16]; this indicated a minimum required sample size of N = 186, confirming that the final sample of N = 290 was fully adequate for the multivariable analyses.

2.4. Measurements and Instruments

Subjective QoL was assessed using the Vietnamese validated version of the World Health Organization Quality of Life Brief Version (WHOQOL-BREF) [5]. The instrument consists of 26 self-report items rated on a 5-point Likert scale ranging from 1 to 5. Two items assess overall QoL and general health satisfaction, while the remaining 24 items are organized into four specific domains. The Physical Health domain comprises seven items assessing activities of daily living, dependence on medicinal substances, energy and fatigue, mobility, pain and discomfort, sleep and rest, and work capacity. The Psychological domain consists of six items covering bodily image and appearance, positive and negative feelings, self-esteem, spirituality or religion, and thinking, learning, and memory. The Social Relationships domain includes three items addressing personal relationships, social support, and sexual activity. The Environment domain comprises eight items assessing financial resources, physical safety and security, accessibility of health and social care, home environment, opportunities for recreation, physical environment, and transportation. Raw scores for each domain were calculated according to the standard WHOQOL-BREF scoring guidelines and subsequently transformed linearly to a standardized 0–100 scale. Higher scores indicate better subjective QoL [5].

Depressive symptom severity during the preceding seven days was assessed using the Vietnamese validated version of the Quick Inventory of Depressive Symptomatology–Self Report (QIDS-SR16) [2,17,18]. The QIDS-SR16 evaluates the nine diagnostic symptom domains of major depressive disorder, with total scores ranging from 0 to 27. According to the established scoring criteria, total scores of 0–5 indicate no or minimal depressive symptoms, 6–10 indicate mild depression, 11–15 indicate moderate depression, 16–20 indicate severe depression, and 21–27 indicate very severe depression [17].

Contextual and clinical variables were assessed to characterize factors potentially relevant to participants’ daily health management and QoL. Perceived time availability for self-care was measured using a single self-report item asking, “Over the past two weeks, how would you rate the availability of time you have to engage in personal self-care and restorative activities?” Responses were categorized into four ordinal levels: Ample time, Sufficient time, Limited time and No time. This item was designed to capture participants’ subjective perception of discretionary time available for personal self-care and restorative activities.

Perceived economic status was assessed based on participants’ self-evaluation of their socioeconomic condition and categorized into four levels: High-income, Adequate income, Low income and Very low income. Illness duration was obtained from verified medical records and patient report, and categorized as <1 year, 1–5 years, or ≥6 years. Sociodemographic and clinical covariates included age, sex (male/female), place of residence (Ho Chi Minh City vs. other provinces), marital status (single, married/cohabitating, separated/divorced/widowed), living arrangements (with family, with friends, or alone), and body mass index (BMI, kg/m²).

2.5. Statistical Analysis

Statistical analyses were performed using Stata version 14.0 (StataCorp, College Station, TX, USA). Descriptive statistics were computed to summarize sample characteristics; continuous variables were presented as means ± standard deviations (sd), and categorical variables as frequencies and percentages (n, %).

To identify independent determinants of QoL across the four WHOQOL-BREF domains, four separate multivariable linear regression models were constructed. Standard simultaneous entry was applied for all potential predictor variables: age, sex, residence, marital status, living arrangement, perceived economic status, perceived time availability for self-care, BMI, QIDS-SR16 score, and illness duration.

To address potential heteroskedasticity, robust standard errors (SE) were applied. Statistical significance was defined as two-tailed p < 0.05. Model parameter estimates are reported, including unstandardized regression coefficients (β), 95% confidence intervals (95% CI), SE, and p-values, representing the change in WHOQOL-BREF domain scores (expressed in points on a 0–100 scale) per unit change in each predictor variable. Model fit was evaluated using R², adjusted R², F-statistic, and overall model p-value. Multicollinearity among predictors was systematically evaluated using Variance Inflation Factor (VIF) and Tolerance statistics; all VIF values were below 3.0 (mean VIF = 1.47), confirming that multicollinearity was not a concern. Standardized regression residuals were examined visually and via normal probability plots to verify linear regression assumptions. Missing data were absent as all 290 enrolled participants completed the paper-based survey administered by trained research assistants.

3. Results

3.1. Participant Characteristics

During the study period, 300 outpatients were screened for eligibility. Two individuals were excluded because they were under 18 years of age at the time of data collection, leaving 298 eligible patients. Of these, five declined to participate, resulting in 293 enrolled participants. Subsequently, three participants were excluded due to incomplete responses on the QIDS-SR16 questionnaire, as complete item responses were required to compute a valid total depressive severity score. The final analytic sample comprised 290 outpatients with MDD. The participant’s sociodemographic and clinical characteristics are summarized in

Table 1. Participant’s sociodemographic and clinical characteristics (N = 290).

Characteristic	Result
Sex, n (%)
Male	83 (28.6)
Female	207 (71.4)
Age, mean ± sd	40.2 ± 17.4
Place of residence, n (%)
Ho Chi Minh City	91 (31.4)
Other	199 (68.6)
Marital status, n (%)
Single	107 (36.9)
Married/Cohabitating	159 (54.8)
Separated/Divorced/Widowed	24 (8.3)
Living arrangement, n (%)
With family	231 (79.7)
With friends	20 (6.9)
Alone	39 (13.4)
Perceived economic status, n (%)
High-income	43 (14.8)
Adequate income	215 (74.1)
Low/Very low income	33 (11.1)
Perceived time availability for self-care, n (%)
Ample time	38 (13.1)
Sufficient time	197 (67.9)
Limited time/No time	55 (19.0)
Body mass index, mean ± sd	22.7 ± 3.6
Illness duration, n (%)
Less than 1 year	237 (81.7)
1 to 5 years	40 (13.8)
6 years or more	13 (4.5)
QIDS-SR16 score, mean ± sd	13.6 ± 5.5
WHOQOL-BREF domain scores (0–100 scale), mean ± sd
Physical health	45.2 ± 12.1
Psychological health	46.3 ± 12.7
Social relationships	52.6 ± 12.9
Environment	53.0 ± 10.3

sd: standard deviation.

.

The mean age of participants was 40.2 ± 17.4 years. The majority were female (71.4%, n = 207), resided outside Ho Chi Minh City (68.6%, n = 199), and lived with family members (79.7%, n = 231). More than half of the sample were married or cohabitating (54.8%, n = 159). Regarding subjective economic status, 74.1% (n = 215) described their financial condition as “Adequate”, while 11.1% (n = 32) reported “Low/Very low income”. A total of 67.9% (n = 197) perceived their time availability for self-care as “Sufficient,” whereas 19.0% (n = 55) reported “Limited time/No time.”

Clinically, the mean QIDS-SR16 score was 13.6 ± 5.5, corresponding to the moderate depressive symptom severity range. Regarding illness duration, 81.7% (n = 237) had been diagnosed for less than 1 year, 13.8% (n = 40) for 1 to 5 years, and 4.5% (n = 13) for 6 years or more.

3.2. Multivariable Linear Regression Analyses of Quality of Life Domains

Four separate multivariable linear regression models with robust standard errors were constructed to identify independent predictors of WHOQOL-BREF domain scores (

Table 2. Multivariable linear regression analyses predicting WHOQOL-BREF domain scores (N = 290).

Predictor Variable	Physical Health, β (SE) [95% CI]	Psychological Health, β (SE) [95% CI]	Social Relationships, β (SE) [95% CI]	Environment, β (SE) [95% CI]
Age	0.03 (0.05) [−0.06, 0.12]	0.16 (0.04) [0.07, 0.25]  a	0.07 (0.05) [−0.04, 0.17]	−0.06 (0.05) [−0.16, 0.03]
Sex (Ref: Male)
Female	−0.99 (1.20) [−3.36, 1.38]	−0.99 (1.24) [−3.43, 1.44]	2.11 (1.39) [−0.64, 4.85]	−0.79 (1.06) [−2.78, 1.38]
Place of residence (Ref: Ho Chi Minh City)
Other provinces	0.31 (1.28) [−2.21, 2.84]	−0.50 (1.21) [−2.88, 1.89]	1.25 (1.59) [−1.89, 4.38]	0.81 (1.03) [−1.23, 2.84]
Marital status (Ref: Single)
Married/Cohabitating	3.21 (2.01) [−0.75, 7.16]	2.65 (2.18) [−1.64, 6.94]	8.84 (2.36) [4.19, 13.49] a	1.54 (2.12) [−2.63, 5.72]
Separated/Divorced/Widowed	3.33 (2.89) [−2.36, 9.01]	−2.06 (2.71) [−7.40, 3.29]	0.83 (2.97) [−5.02, 6.69]	−1.13 (2.58) [−6.21, 3.95]
Living arrangement (Ref: With family)
With friends	−2.37 (2.40) [−7.09, 2.36]	−3.38 (2.29) [−7.88, 1.11]	−2.58 (2.39) [−7.28, 2.11]	−0.39 (2.26) [−4.83, 4.05]
Alone	3.94 (2.58) [−1.14, 9.01]	−1.51 (2.42) [−6.28, 3.26]	−0.98 (3.55) [−7.96, 6.00]	2.98 (2.87) [−2.66, 8.62]
Perceived economic status (Ref: High-income)
Adequate income	0.65 (1.84) [−2.96, 4.27]	−3.72 (1.68) [−7.03, −0.40] a	−4.58 (1.96) [−8.44, −0.72] a	−6.61 (1.56) [−9.68, −3.54] c
Low/Very low income	1.00 (2.52) [−3.95, 5.96]	−4.25 (2.15) [−8.48, 0.03]	−5.62 (2.90) [−11.33, −0.09] a	−12.16 (2.52) [−17.61, −7.69] c
Perceived time for self-care (Ref: Ample time)
Sufficient time	1.87 (2.63) [−3.31, 7.05]	−0.13 (1.96) [−4.00, 3.74]	−1.35 (2.79) [−6.84, 4.13]	−1.60 (1.75) [−5.03, 1.84]
Limited time/No time	−1.91 (3.26) [−8.33, 4.51]	−3.86 (2.73) [−9.22, 1.51]	−6.15 (3.86) [−13.75, 1.46]	−6.65 (2.45) [−11.47, −1.83] b
Body mass index	0.12 (0.20) [−0.28, 0.51]	−0.38 (0.16) [−0.70, −0.07] a	−0.13 (0.22) [−0.56, 0.30]	−0.06 (0.17) [−0.41, 0.28]
QIDS-SR16 score	−1.17 (0.13) [−1.43, −0.92] c	−1.20 (0.12) [−1.43, −0.97] c	−0.57 (0.16) [−0.88, −0.27] c	−0.64 (0.11) [−0.86, −0.42] c
Illness duration (Ref: 1 to 5 years)
Less than 1 year	−5.21 (2.70) [−10.52, −0.10] a	−5.33 (2.47) [−10.20, −0.47] a	−1.90 (2.80) [−7.42, 3.62]	−4.73 (2.26) [−9.18, −0.28] a
6 years or more	1.61 (4.18) [−6.62, 9.83]	1.96 (3.54) [−5.00, 8.93]	1.72 (6.88) [−11.83, 15.27]	−2.44 (4.08) [−10.47, 5.59]
Constant	59.68 (7.17) [45.56, 73.80] c	75.28 (5.65) [64.16, 86.39] c	64.52 (6.90) [50.94, 78.11] c	77.62 (5.20) [67.37, 87.86] c
Model Fit Statistics
R2	0.435	0.479	0.304	0.391
Adjusted R2	0.404	0.450	0.266	0.358
Model F-statistic (df)	F(17, 272) = 14.44	F(17, 272) = 20.81	F(17, 272) = 9.72	F(17, 272) = 12.33
Model p-value	p < 0.001	p < 0.001	p < 0.001	p < 0.001

Note: β = unstandardized regression coefficient (expressed as points on the 0–100 WHOQOL-BREF scale); SE = robust standard error; CI = confidence interval; Ref = reference category; QIDS-SR16 = Quick Inventory of Depressive Symptomatology–Self Report. Robust standard errors were applied to account for potential heteroskedasticity. Statistically significant estimates are highlighted in bold: ^a: p < 0.05, ^b: p < 0.01, ^c: p < 0.001.

).

The multivariable linear regression model explained 43.5% of the total variance in physical health QoL (R² = 0.435, adjusted R² = 0.404, F_{(17, 272)} = 14.44, p < 0.001). Depressive symptom severity was the strongest independent negative predictor (β = −1.17, SE = 0.13, p < 0.001, 95% CI: −1.43–−0.92). Having an illness duration of less than 1 year (compared to 1–5 years) was significantly associated with lower physical QoL scores (β = −5.21, SE = 2.70, p = 0.044, 95% CI: −10.52–−0.10). Age, sex, place of residence, marital status, living arrangement, perceived economic status, perceived time availability for self-care, and BMI did not exhibit statistically significant independent associations with physical QoL.

The psychological QoL model accounted for 47.9% of the outcome variance (R² = 0.479, adjusted R² = 0.450, F_{(17, 272)} = 20.81, p < 0.001). QIDS-SR16 score was strongly negatively associated with psychological QoL (β = −1.20, SE = 0.12, p < 0.001, 95% CI: −1.43–−0.97). Older age was independently associated with higher psychological QoL (β = 0.16, SE = 0.04, p < 0.001, 95% CI: 0.07–0.25). Conversely, lower perceived economic status (“Adequate income” vs. “High income”: β = −3.72, SE = 1.68, p = 0.030, 95% CI: −7.03–−0.40), higher BMI (β = −0.38, SE = 0.16, p = 0.018, 95% CI: −0.70–−0.07), and illness duration of less than 1 year (vs. 1–5 years: β = −5.33, SE = 2.47, p = 0.037, 95% CI: −10.20–−0.47) independently predicted lower psychological QoL.

The social relationships model accounted for 30.4% of variance (R² = 0.304, adjusted R² = 0.266, F_{(17, 272)} = 9.72, p < 0.001). QIDS-SR16 score remained an independent negative predictor (β = −0.57, SE = 0.16, p < 0.001, 95% CI: −0.88–−0.27). Married or cohabitating participants reported substantially higher social QoL compared to single participants (β = 8.84, SE = 2.36, p < 0.001, 95% CI: 4.19–13.49). Compared to participants with a high income, reporting an ‘Adequate’ economic status was independently associated with lower Social QoL (β = −4.58, SE = 1.96, 95% CI: −8.44–−0.72, p = 0.02), with a slightly greater reduction observed among those reporting a “Low/Very low income” (β = −5.62, SE = 2.90, 95% CI: −11.33–−0.09, p = 0.044).

The environmental QoL model explained 39.1% of the total variance (R² = 0.391, adjusted R² = 0.358, F_{(17, 272)} = 12.33, p < 0.001). QIDS-SR16 score negatively predicted environmental QoL (β = −0.64, SE = 0.11, p < 0.001, 95% CI: −0.86–−0.42). A strong socioeconomic gradient was observed, with progressively lower environmental QoL reported by participants with “Adequate income” (β = −6.61, p < 0.001) and “Low/Very low income” (β = −12.16, p < 0.001) relative to those with “High income.” Notably, perceived time constraint (“Limited time/No time for self-care”) was an independent negative predictor of environmental QoL (β = −6.65, SE = 2.45, p = 0.007, 95% CI: −11.47–−1.83). Illness duration under 1 year was also associated with lower environmental QoL (β = −4.73, SE = 2.26, p = 0.027, 95% CI: −9.18–−0.28).

4. Discussion

This cross-sectional study evaluated multidimensional QoL and its sociodemographic, clinical, and contextual correlates among 290 outpatients with MDD in Ho Chi Minh City, Vietnam. By constructing four domain-specific multivariable linear regression models applying robust standard errors, our study explained substantial variance across physical health (44.1%), psychological health (47.9%), social relationships (30.5%), and environmental (39.6%) QoL domains. The empirical findings provide important insights into how depressive symptom severity, perceived time availability for self-care, illness duration, and subjective socioeconomic standing independently shape patient-reported well-being in an urban LMIC setting.

4.1. Depressive Symptom Severity as the Most Consistent Correlate Across All QoL Domains

In alignment with our primary hypothesis and extensive international literature [1,2,4,6,7], depressive symptom severity evaluated by the QIDS-SR16 score emerged as the single most robust and consistent negative predictor of QoL across all four WHOQOL-BREF domains (p < 0.001). Every 1-point increase in QIDS-SR16 score was independently associated with a reduction of 1.17 points in physical QoL, 1.20 points in psychological QoL, 0.64 points in environmental QoL, and 0.57 points in social QoL. Depressive pathology directly impairs neurocognitive functioning, emotional regulation, physical vitality, and social motivation [3], which pervasively degrades subjective well-being across spheres of daily living. This pervasive impact explains why clinical symptom severity accounts for the largest share of unique variance in physical and psychological health domains. Core depressive symptom reduction remains a fundamental prerequisite for restoring patient QoL in routine psychiatric practice [2]. Nevertheless, clinical severity alone does not fully account for multidimensional QoL outcomes, as evidenced by model R-squared values ranging from 30.5% to 47.9%. This finding reaffirms that QoL is a broad, multidimensional construct influenced by contextual, socioeconomic, and lifestyle factors beyond pharmacologically driven symptom control [1,4].

4.2. Perceived Time Availability for Self-Care and Environmental Quality of Life

A key objective of this study was investigating the contextual variable “perceived time availability for self-care”. In our multivariable regression model, reporting limited time or no time for self-care independently predicted a 6.65-point reduction in environmental QoL (β = −6.65, SE = 2.45, p = 0.007), controlling for economic status and symptom severity. Notably, perceived time availability showed no independent associations with physical, psychological, or social QoL domains.

The domain-specific link between perceived time availability and environmental QoL is conceptually coherent. The WHOQOL-BREF Environmental domain evaluates physical safety, home surroundings, financial security, transportation, and opportunities for recreation and leisure [5]. In a rapidly modernizing metropolis like Ho Chi Minh City, urban life places heavy commuting, occupational, and domestic caregiving demands on individuals [11,12]. When discretionary time for restorative self-care activities is severely constrained, patients perceive their immediate living environment as restrictive and stressful.

Several conceptual and methodological nuances regarding this finding warrant discussion. Perceived time availability for self-care was measured using a single self-report item evaluating subjective discretionary time over the preceding two weeks. This construct captures an individual’s personal appraisal of time availability for restorative activities rather than a validated, objective macro-structural time poverty index. Framing this finding as an exploratory association avoids overclaiming structural causality while recognizing its clinical relevance. In addition, because all variables were self-reported, common-method bias may inflate associations between subjective perceptions of time constraints and environmental QoL. Furthermore, reverse causality remains plausible, as greater depressive symptom burden or cognitive distortion may cause patients to perceive their schedule as overwhelming and report severe time lack. Alternatively, actual time pressure may restrict self-care behaviors, thereby exacerbating environmental dissatisfaction. This cross-sectional observation represents an exploratory association that warrants prospective verification using validated multidimensional time-use tracking.

4.3. Influence of Illness Duration: Initial Diagnosis Burden Versus Long-Term Course

Regarding illness duration, patients diagnosed within the past year (81.7%, n = 237) reported significantly lower QoL scores across physical (β = −5.21, p = 0.044), psychological (β = −5.33, p = 0.037), and environmental (β = −4.73, p = 0.027) domains compared to those with an illness duration of 1 to 5 years (13.8%, n = 40). This relationship highlights the distinct burden experienced during the initial clinical course. During the first year following an MDD diagnosis, patients often experience acute psychological disruption, illness-related self-stigma, adjustment to psychiatric medications, and occupational or family disruption, resulting in lower subjective QoL. Over 1 to 5 years, patients may develop stabilized coping mechanisms, adjust personal expectations, and benefit from continuous outpatient care. Participants with an illness duration of 6 years or more comprised only 4.5% (n = 13) of the cohort. In the regression model, this subgroup did not differ significantly from the 1 to 5 year reference group (β = 1.61, p = 0.753 for physical QoL; β = 1.96, p = 0.583 for psychological QoL). Small subgroup sample sizes generate wide confidence intervals and unstable statistical estimates, requiring cautious interpretation. Furthermore, while chronic disease framework theories suggest that long-term patients may undergo response shifts or psychological adaptation [13,14], cross-sectional data cannot establish individual adaptation trajectories over time. Alternative explanations for higher QoL in longer-duration subgroups include selection or survival bias, wherein patients who remain in outpatient care for over six years represent a resilient or treatment-responsive subpopulation, whereas non-adaptive or severely impaired patients drop out or require institutional care. Differential healthcare access and cohort effects may also contribute to these cross-sectional differences.

4.4. Socioeconomic, Relational, and Demographic Determinants

Our multivariable models revealed a pronounced socioeconomic gradient in Environmental QoL. Compared to high-income patients, those reporting adequate income (β = −6.61, p < 0.001) and low or very low income (β = −12.16, p < 0.001) experienced marked decrements in environmental QoL. Financial strain directly restricts access to quality housing, transportation, recreational activities, and healthcare in LMICs [8,9]. Reporting an adequate income was also associated with lower psychological (β = −3.72, p = 0.028) and social QoL (β = −4.58, p = 0.022) relative to high income.

Marital status was the single strongest independent predictor of Social Relationships QoL. Married or cohabitating patients scored 8.83 points higher in social QoL relative to single patients (β = 8.84, SE = 2.36, p < 0.001), underscoring the buffering role of partner social support in Asian family-oriented cultural settings [8,15]. Older age was independently associated with higher psychological QoL (β = 0.16, p < 0.001), consistent with prior literature indicating greater emotional maturity or recalibrated expectations among older adults [19]. Higher body mass index was associated with lower psychological QoL (β = −0.38, p = 0.018), likely reflecting body image dissatisfaction and physical comorbidity burdens.

4.5. Limitations

Several limitations must be acknowledged. The observational cross-sectional design precludes establishing causality or temporal directionality between time availability, clinical severity, and QoL. Perceived time availability for self-care was assessed using an unvalidated single self-report question with a two-week recall period rather than an objective time-use diary or validated time-poverty scale. Important potential confounders—such as exact weekly working hours, shift work, caregiving responsibilities, comorbid anxiety disorders, physical comorbidities, and specific antidepressant regimens—were not collected and could not be controlled for. Illness duration relied partly on patient self-report, introducing potential recall bias. Operationalizing clinical stability as eight or more weeks on an unchanged medication regimen does not guarantee complete remission, as the mean QIDS-SR16 score (13.6 ± 5.5) indicates moderate ongoing depressive symptoms. Finally, the sample was heavily skewed toward patients diagnosed within one year (81.7%), leaving small subgroup sizes for long-duration illness.

5. Conclusions

In summary, this cross-sectional study demonstrates that depressive symptom severity is the most consistent correlate of multidimensional QoL among Vietnamese outpatients with MDD, while shorter illness duration (<1 year) and subjective financial strain are independently associated with reduced QoL across multiple domains. Notably, perceived time availability for self-care exhibits a domain-specific association exclusively with Environmental QoL.

Based on these empirical observations, routine psychiatric outpatient care may benefit from expanding beyond pharmacological symptom reduction to consider patients’ environmental, financial, and lifestyle constraints, including self-care time availability. Patients in the initial year following diagnosis warrant particular attention, as targeted psychoeducation and social support during this transition may assist with coping and adaptation. Finally, given the cross-sectional nature of these findings, future longitudinal studies utilizing objective time-use metrics and prospective designs are required to evaluate the causal trajectories connecting lifestyle constraints, self-care availability, and long-term QoL outcomes.