Depressive Symptoms among Cancer Patients in a Philippine Tertiary Hospital: Prevalence, Factors, and Influence on Health-Related Quality of Life

Abstract

Background

The World Health Organization recognizes depression as one of the most burdensome diseases in the world. Among cancer patients, depression is significantly associated with shorter survival, independent of the influence of biomedical prognostic factors. Although cancer is the third leading cause of morbidity and mortality among Filipinos, little is known about depressive symptoms and their influence on health-related quality of life in this population. We assessed the prevalence of, and factors associated with, depressive symptoms and their influence on health-related quality of life in Filipino patients with cancer.

Methods

The Patient Health Questionnaire (PHQ)-8 and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 were administered to all inpatients and outpatients, age >=18 years presenting for cancer treatment.

Results

Twenty-two percent (n=53/247) were categorized as depressed, using a PHQ-8 cutoff of ≥10. Depressed patients scored lower on cognitive, emotional, role, physical, and social functioning than those who scored PHQ<10 (all P<0.001). Depression varied by disease status, performance status and marital status (all P<0.001). However, only performance status (OR [odds ratio]=2.20; 95% CI=1.60, 3.00) and disease status (OR=2.4; 95% CI=1.13, 5.22) were significantly associated with depression in the multivariable model.

Conclusions

Depression is prevalent in Filipino cancer patients. The findings provide empirical support for the development of mental health services in this understudied population. This study, the first to assess the prevalence of and factors associated with depression in Filipino cancer patients, needs further validation.

Background

The World Health Organization recognizes depression as one of the most burdensome diseases in the world¹. Among patients with cancer, depression can be a major source of distress²and may have a profound impact on disease progression. Clinically significant depression in patients with cancer is estimated to be 11–30%, a rate two to five times greater than in the general population.^3–5

Cancer is the third leading cause of mortality in the Philippines. However, there has been no study of depressive symptoms in Filipino cancer patients. Therefore, we assessed the prevalence of depressive symptoms and determined the factors associated with depressive symptoms in this population. We also assessed the relationship between depressive symptoms and health-related quality of life.

Materials and Methods

We surveyed inpatients and outpatients, age 18 years or older, presenting for cancer treatment at the University of Santo Tomas Hospital Benavides Cancer Institute (USTH-BCI), a nonprofit tertiary hospital in Manila, Philippines, that sees about 3,000 cancer patients annually. This study was approved by the institutional review board of USTH-BCI.

Instruments

All surveys were conducted in person using self-administered questionnaires. Depressive symptoms were assessed using the Patient Health Questionnaire (PHQ)-8. We used the Tagalog version of the PHQ-8, which has undergone the requisite translation and back-translation process. PHQ-8 excludes the item on suicidal ideation. Response options, on a four-point (0–3) scale, were tallied to produce a total score of 0–24 points.⁶ A PHQ-8 score ≥10 has a sensitivity of 88% and a specificity of 88% for a diagnosis of major depression.^6–7 For this study, we found internal consistency reliability, Cronbach's α=0.84, for the PHQ-8.

Health-related quality of life (HRQoL) was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30); version 3, designed to assess health-related quality of life in patients participating in oncologic studies.⁸ We used the Tagalog version of the EORTC-QLQ-30.⁹ For this study, we found internal consistency reliability, Cronbach's α=0.83, for the EORTC-QLQ-C30.

The patient's performance status was rated on a scale of 0 (“fully active, able to carry on all pre-disease performance” to 4 (“completely disabled, totally confined to bed or chair”) as developed by the Eastern Cooperative Oncology Group (ECOG).¹⁰

Statistical Analyses

Descriptive statistics were used to summarize patient characteristics. We dichotomized our sample into: with (≥10 points for the PHQ-8 total score) and without depression (<10 points). We conducted logistic regression analysis to assess the factors associated with depression. Candidate variables included sociodemographic characteristics (gender, age, educational level, marital status), disease-related variables (primary cancer diagnosis; metastatic; performance status) and comorbid conditions. To obtain the most parsimonious model, only variables with P values<0.05 were included in the final model. We also compared the EORTC-QLQ-C30 subscale scores of depressed versus nondepressed patients. The SPSS version 17 was used in the analyses.

Results

A total of 271 patients participated in the survey (94% response rate). The most common cancers were breast (31%), head and neck (12%), and lung (11%). Seventy-three percent had nonmetastatic disease and 45% were fully active with regard to their performance status. The most common comorbidities were hypertension (41%) and diabetes (11%).

Table 1 shows endorsement of the PHQ-8 items. Panel B shows that 26% of the patients responded that on more than half of the days or nearly every day, they feel tired or have little energy, have trouble falling/staying asleep (25%), feel bad about themselves (22%), have little interest or pleasure in doing things (21%) and feeling down, depressed, or hopeless (19%).

Table 1.

Endorsement of the PHQ-8 Items

PHQ-8 Items	Panel A Not at all or for several days n (%)	Panel B More than half of the days or nearly every day n (%)
Little interest or pleasure in doing things	198 (79)	54 (21)
Feeling down, depressed, or hopeless	203 (81)	49 (19)
Trouble falling/staying asleep; sleeping too much	188 (75)	62 (25)
Feeling tired or having little energy	184 (74)	66 (26)
Poor appetite; overeating	208 (83)	43 (17)
Feeling bad about yourself or that you are a failure or have let yourself or your family down	197 (78)	55 (22)
Trouble concentrating, such as reading the newspaper or watching television	216 (86)	26 (14)
Moving or speaking so slowly that other people may have noticed	216 (86)	35 (14)

Some PHQ-8 items were not completed.

Of the 247 patients who completed all the PHQ items, 22% (n=53) were categorized as depressed (PHQ-8≥10). Depression (Table 2, Panel A) significantly varied by disease status (p<0.05), performance status (p<0.05), and marital status (p<0.05).

Table 2.

Prevalence of Depression and Factors Associated with Depression

Panel A: Prevalence of Depression
Variables	PHQ-8≥10 n (%)
Gender
Male	21 (24)
Female	32 (21)
Age
<53	26 (23)
≥53	26 (20)
Education
<High school	5 (17)
High school graduate	16 (32)
Some college	9 (21)
College graduate	24 (22)
More than college	0 (0)
Marital status
Married	38 (23)*
Single	5 (13)
Separated	2 (15)
Widowed	9 (43)
Employment status
Full time	11 (18)
Retired	15 (21)
Not employed	27 (25)
Primary cancer diagnosis†
Breast	14 (18)
Head and neck	14 (45)
Lung	6 (24)
Brain	3 (27)
Lymphoma	2 (17)
Leukemia	2 (17)
Stage of disease
Nonmetastatic	31 (17)*
Metastatic	22 (36)
ECOG performance status
0	11 (10)*
1	17 (20)
2	10 (45)
3	9 (47)
4	6 (86)

PHQ-8≥10 indicates depression; ^*, Chi-square ^*p-value<0.05; †= top 6 diagnoses

Panel B: Factors Associated with Depression
Variables**	OR 95% Confidence Interval P value
Stage of disease
Nonmetastatic	1.0
Metastatic	2.4
	1.13, 5.22
	0.02
ECOG performance status***
0	1.0
1–4	2.20
	1.60, 3.00
	0.001

^**, Candidate variables assessed included disease-related (i.e., primary cancer site, metastasis, ECOG performance status), comorbid conditions, and sociodemographic factors (sex, age, educational level, marital and employment status); OR=odds ratio; ^***, ECOG performance status analyzed as a continuous variable with zero as reference.

Bivariate analysis showed that performance status and metastatic disease were significant correlates of depression. We found that those with metastasis to the bone were at a higher risk for being depressed (p=0.03) and that single and separated patients were less likely to report depression than married patients. Although marginally significant, those who were widowed were two-and-a-half times more likely to be depressed than those who were married. Only performance status (OR=2.20; 95% CI=1.60, 3.00; p<0.001) and metastatic disease (OR=2.4; 95% CI=1.13, 5.22; p=0.02) persisted in the multivariable analyses (Panel B).

Depression and Health-Related Quality of Life

Because the EORTC QLQ-C30 score was not normally distributed (p<0.001), we used non-parametric Mann Whitney U to assess the association of PHQ-8≥10 with EORTC QLQ-C30 subscales. Those who were depressed (PHQ-8≥10) had lower cognitive, emotional, role, physical, and social functioning than those who scored PHQ<10 (all Ps<.001).

Discussion

This is the first study to examine the prevalence of depressive symptoms in Filipino cancer patients and to document the association of depression with impaired quality of life in this understudied population. As many as 22% cancer patients scored as depressed. This is consistent with studies in other countries showing 15 to 30% depression in cancer patients.^3–4 Not surprisingly, self-reported depression in our sample was associated with reduced quality of life on all major subscales of the EORTC.

An examination of factors associated with depression found that patients with metastatic disease were at higher risk for being depressed. To further explore the relationship between metastasis and depression, we conducted subgroup analysis and found that those with metastasis to the bone, a painful condition, were at a higher risk for being depressed.¹¹ Many have proposed that pain may share a common biological mechanism with depression.^12–16 Indeed, studies have begun to explore inflammation as a biological mechanism that may underlie pain and depressive symptoms in cancer patients.^13–14 Such molecular studies should be explored in Filipino patients with cancer.

The literature suggests that depression can be reliably diagnosed in primary care and oncology settings. It has also been shown that antidepressant medications and brief psychotherapy are effective for 60% to 80% of those affected.¹⁷ Thus, all patients with cancer should be assessed for depressive symptoms and receive treatment if they are experiencing depression. In developing countries such as the Philippines, barriers to effective care include lack of resources, including trained providers, and the social stigma associated with mental disorders. The World Health Organization's initiative on depression in public health hopes to reduce the impact of depression by closing the “treatment gap” between available cost-effective treatments and untreated individuals.¹ The programs developed by this initiative may help to address issues of limited resources in the Philippines.

Nineteen percent of the patients reported feeling depressed or down on more than half of the day or nearly every day, a diagnostic criterion for major depression. Because the PHQ uses multiple symptoms of depression, 22% were categorized as depressed using the eight-item PHQ. Therefore, the PHQ-8 may be a particularly useful screening tool in this patient population because it screens for depression with several different questions and provides an easier way for cancer patients to convey to their providers that they are depressed. This is important because studies suggest that cancer patients may hesitate to disturb their physician by reporting distress and may even have a negative attitude toward depression.^{18, 19} Short assessment measures such as the PHQ-8 may be effective in identifying patients who are experiencing depressive symptoms. Additional research is needed to identify the best strategy to screen for depression among Filipino patients with cancer. Furthermore, randomized clinical trials are needed to determine if screening for depression improves depression outcomes.²⁰

Surprisingly, single and separated patients were less likely to report depression than married patients. In contrast, in studies of the general population, singles, especially men, typically report higher rates of depression than the married.²¹. The small numbers of patients in the single and separated subgroups in our study makes interpretation of these findings difficult. Our results also indicated that those who were widowed were two-and-a-half times more likely to be depressed than those who were married. This is consistent with studies showing that marriage provides additional social and emotional support that may be important when adapting to the stress associated with cancer.²² Given that Filipinos regard the family as the basic unit of society and a primary source of social support, future studies should incorporate measures of social resources and support.²³

Our study has limitations. Our sample was recruited at one tertiary care cancer center and may not be generalizable to other oncology settings in the Philippines. Nonetheless, the findings provide important insights for future studies that will help improve mental health services in this population. Although we had adequate power to obtain a reliable estimate of the prevalence of depressive symptoms, which was the primary aim of our study, we had limited power to detect associations between depression and some of the demographic and disease-related variables. The cross-sectional study design also prevents any assumptions about causality in the relation between depression and the variables measured.

Another limitation is the lack of a structured psychiatric interview to diagnose a depressive disorder. Clinical depression typically is diagnosed using standardized criteria that include symptoms related to mood, cognition, and neurovegetative function. For a diagnosis of depression, the symptoms must be present for at least two weeks and must interfere with function.²⁴ Although our study did not include a psychiatric interview, the results of several studies of medical patients, including those with cancer, and a large population-based survey confirmed the reliability and validity of the PHQ-8 as a diagnostic measure of depression.^{6, 25–29} No consensus exists, however, regarding the diagnosis of depression in patients with cancer. The PHQ-8 contains somatic and cognitive items (e.g., fatigue, sleep disturbance, difficulty concentrating) that may be related to cancer or its treatment as well as to depression. The inclusion or exclusion of these symptoms when diagnosing depression in patients with cancer is debated.^30–31 Recent research results have demonstrated, however, that the somatic and cognitive symptoms and depression share common pathophysiology and respond to similar treatments.³² Thus, the use of all symptoms traditionally included in a diagnosis of depression is often recommended for patients with cancer.^{30, 33}

In conclusion, depression is prevalent and is significantly associated with reduced quality of life in this sample of Filipino patients with cancer. Assessment of depression is an important aspect of quality cancer care to help improve the well-being of patients³⁴. This study is the first to assess the prevalence of depressive symptoms in Filipino cancer patients. The findings provide empirical support for the need for screening for depression and providing mental health services in order to improve the overall well-being of this understudied population.

Author Disclosure Statement

No competing financial interests exist.