PHQ-9 DIAGNOSTIC ACCURACY AND OPTIMAL CUT-OFF FOR DEPRESSIONAMONG PATIENTS WITH STROKE IN NIGERIA

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I.N. Okeafor1, C.U. Okeafor2

1. Department of Public Health, Federal Ministry of Health, Nigeria. 
2. Department of Mental Health, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria.

Abstract

Background: Depression is one of the most common and devastating consequences among stroke survivors. In spite of the availability of treatment for depression, the non- or under-detection precludes patients from benefiting
from it.

Objectives: This study sought to validate the Patient Health Questionnaire (PHQ9) as a tool for detecting depression among patients with stroke.

Methodology: A cross-sectional design comprising of adult patients diagnosed with stroke, who were attending the Neurology out-patient clinic of the University of Port Harcourt Teaching Hospital was employed in the study. The Receiver Operator Characteristics (ROC) curve and validity tests were performed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (SCID-DSM IV) as the gold standard. The optimal PHQ-9 cut-off was determined using Youden Index. Kappa statistics was performed at p<0.05.

Results: The study had a total of 197 stroke cases with PHQ-9 and SCID-DSM IV findings. The median age was 54 years (range: 35-76 years). ROC Curve for PHQ-9 revealed an Area under the Curve (AUC) value of 0.93(95% CI: 0.88- 0.98). The optimal cut off value of six was obtained based on Youden Index. Sensitivity, specificity, positive predictive and negative predictive values at the optimal cut-off were 88.7%, 93.1%, 82.5% and 95.7% respectively. The Kappa statistics yielded 0.80 (95% CI: 0.68-0.86).

Conclusion: PHQ-9 is a useful screening tool for identifying depression among patients with stroke. An optimal cut-off score of six for PHQ-9 should be adopted for patients with stroke in Nigeria to identify depression, and the provision of
holistic care.

Keywords: Stroke, Depression, PHQ-9, Validity, Optimal cut-off.

Introduction

Globally, stroke has been recognized as a major health problem, largely due to the negative effect on the physical and mental wellbeing of the affected individual.¹ Stroke, also known as Cerebrovascular Accident (CVA) has been defined as a rapidly developing clinical features of focal or global neurological deficit, lasting twenty-four hours or longer or even leading to death with no apparent cause other than that of vascular origin. ² Beyond the high prevalence of stroke, and being the leading cause of adult physical disability, the sequelae on the mental health of the sufferer is contributing greatly to the burden of stroke especially in low and middle-income countries.¹ Notably, of all the neuropsychiatric
consequence of stroke, depression tops the list, as being the most common.³

Depression is increasingly being recognized as a significant sequelae of stroke across the globe.^4,5 The frequency of depression following stroke ranges from29% to 36%.⁴ Sadly, depression gives a double negative impact in stroke. Firstly, it hinders complete recovery of the stroke victim, which could lead to prolonged hospitalization.⁶ Secondly, depression, though a mental disorder has been shown to increase the risk of cardiovascular disease, which invariably increases the risk of the occurrence of another stroke in the victim.^7,8 Thus, greatly compromising the quality of life of the patient and increasing the mortality risk.9,10

Undoubtedly, the treatment of depression is vital to the improved clinical outcome among affected patients with stroke. Therefore, early recognition of depression is vital in patient care. However, this could be difficult especially in low-resource settings, where the focus in stroke care is solely on the restoration of cognitive and motor function^.11This is not unconnected to the high patient load in the out-patient clinics, which preempts depression screening. Hence, there is a need for a validated, brief, and easy to administer tool for assessing depression among patients with stroke in such settings. This will ensure holistic care and avert the negative aftermath stemming from undiagnosed and subsequently untreated depression.

Notably, several screening tools for depression exist. The Patient Health Questionnaire-9, commonly referred to as PHQ-9 is an easy to administer tool for identifying depression in out-patient settings^.12 The PHQ-9 also has the advantage of being concise, and has been widely used in most primary care settings^.12,13,14 However, its use among patients with stroke is yet to be fully elucidated. Also, the controversy of the optimal cut-off of the tool in identifying depression among patients with stroke necessitates present research. Although, validation studies carried out in primary care settings have found the tool useful.^12,13 The validation findings among patients with stroke is limited, with no optimal cut-off identified for patients with stroke in Nigeria.

This study therefore sought to validate the usefulness of PHQ-9 in diagnosing depression in relation to the gold standard of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (SCID-DSM IV), and also determine the optimal cutoff value of PHQ-9 for depression among patients with stroke.