Prevalence and Associated Factors of Cognitive Impairment Among Stroke Survivors at Comprehensive Specialized Hospitals in Northwest Ethiopia: Multi-Centered Cross-Sectional Study

Introduction

Stroke is the second leading cause of cognitive impairment and disability in adults worldwide.^1,2 According to the WHO, stroke is associated with the world’s fourth highest disease burden.³ Stroke causes cell damage and cell death in the brain, resulting in cognitive dysfunction.⁴ Post-Stroke Cognitive Impairment (PSCI) is one of the most common causes of disability and dependency in stroke survivors.^5,6 It has been reported that it significantly increases the risk of cognitive impairment by 5 to 8 times.^7,8 Cognitive impairment occurs when a person loses focus, executive function, recall, producing and understanding language, problem solving, and decision-making.⁹

Deficits in cognitive function are among the more serious stroke sequelae, delaying and frequently jeopardizing rehabilitation efforts.¹⁰ The prevalence of cognitive impairment after stroke is high worldwide, ranging from 11.6% to 68.2% in various hospital-based studies.¹¹ It was discovered to be 56.3% in Austria,¹² 68.2% in Indonesia,⁴ 21% in Russia,¹³ 54.5% in Singapore,¹⁴ 55% in Portugal,¹⁵ and 63% in Uganda.¹⁶

Post-stroke cognitive impairment (PSCI) is associated with impaired activities of daily living, which may lead to increased use of health-care services, decreased capacity for independent living, and decreased functional performance.¹⁷ PSCI patients are more likely to be re-admitted to the hospital.¹⁸ Patients with stroke who have cognitive impairments in addition to physical impairments have less physical function recovery, more reliance in living after stroke, and a lower quality of life.^19,20 During the first year after a stroke, the costs of care were three times higher for patients with cognitive impairments.²¹

Many factors contribute to cognitive impairment; for example, age and late onset of hospitalization are common risk factors for post-stroke cognitive impairment.^22,23 From age-related risk factors, overweight, high blood pressure, excessive alcohol consumption and sedentary lifestyle are modifiable factor for stroke.²⁴ PSCI prevalence increased with age and peaked at age >70 years (34.7%).⁴ At all-time points, the rate of cognitive impairment in stroke survivors was strongly related to age, and it progressively increased after 5 years of stroke for patients aged 65–85.¹ Low educational attainment is associated with decreased functional cognitive reserve, and it may also influence lifestyle and risk factor profile.²⁵ The higher educational status and personal history of prior stroke help to increase the knowledge of warning signs, risk factors, and prevention mechanisms.²⁶

PSCI was also higher in recurrent stroke survivors.²⁷ When cognitive impairment occurs after a stroke, the patient’s life is significantly impacted, and posing a significant burden on families and society;²⁸ As a result, early detection and elimination of risk factors for cognitive impairment in stroke patients is critical for the effective prevention and treatment of cognitive impairment. According to our extensive search, there is a scarcity of data in Ethiopia on the prevalence and factors associated with cognitive impairment among stroke patients. The purpose of this study was to determine the extent and associated factors of cognitive impairment among stroke survivors in comprehensive specialized hospitals in Ethiopia’s Amhara region.

Methods and Materials

Study Design and Setting

A multi-centered institutional-based cross-sectional study was conducted from April to June 2022 at comprehensive specialized hospitals in Ethiopia’s Amhara region (University of Gondar comprehensive specialized hospital (UOGCSH), Felege Hiwot comprehensive specialized hospital (FHCSH), and Dessie comprehensive specialized hospital (DCSH)) to assess the prevalence of cognitive impairment and associated factors among stroke survivors.

According to the Central Statistics Agency of Ethiopia (CSA), the region’s population in 2015 was estimated to be 24,276,235 people.²⁹ The region has 80 hospitals (4 comprehensive specialized, 4 referral, and 72 primary), 847 health centers, and 3342 health posts.³⁰

Sample Size Determination and Sampling Techniques

A single population proportion formula was used to calculate the sample size. Because no studies on cognitive impairment among stroke survivors were found in our country, any attempt to obtain baseline prevalence from another setting may have an impact on the representativeness of the current study. In order to increase the precision of the study’s results, the maximum sample size assumption was used, with P = 50% prevalence among stroke survivors, a margin of error (d) of 5%, and a 95% level of confidence.

Where =zα/2 = 95% =1.96

p=0.5

q=1-p =1-0.5 =0.5

D =0.05

N = 1.96²×0.5×0.5/0.05²

⁼3.8416×0.25/0.0025

384.37~384;

Taking the 10% non-response rate into account, the final sample size is 422. Proportional allocation was used to determine the number of stroke survivors in each comprehensive specialized hospital. To collect data from each stroke survivor, a systematic random sampling technique was used to select study participants. The study participants were obtained systematically in each comprehensive and specialized hospital using card numbers at every two intervals (k = 2) until the required sample size of 422 was reached.

Variables of the Study

Outcome Variable

The outcome variable in this study was cognitive impairment, which was assessed using the Montreal Cognitive Assessment Basic (MOCAB). It is a brief cognitive screening tool with eight items and a maximum score of thirty. It was designed for people with limited education and varying levels of literacy. Subjects with a MOCAB score of less than 25 were classified as cognitively impaired, while those with a score of more than 25 out of 30 were classified as normal.

Independent Variables

This study’s independent variables were classified as socio-demographic characteristics (age, sex, religion, marital status, occupation, level of education, place of residence). Medical complications (Diabetes mulitas and Hypertension). Clinical factors (hospitalization time, recurrent stroke, dominant hemisphere, stroke type, and time after stroke) as well as personal lifestyle habits (active smoker, excessive alcohol consumption).

Operational Definitions

Cognitive Impairment

When a study subject score ≤25 on the Montreal cognitive assessment basic, they have cognitive impairment.

Smoker

Current smoker defined by CDC as an adult who smokes cigarettes daily/everyday.³¹

Alcoholics

The person who drank two or more bottles of any type of alcohol per day was classified as alcoholic.³²

Eligibility Criteria for Study Participants

All stroke survivors who were attending comprehensive specialized hospitals whose age >18 year were included. However. subjects with a history of Alzheimer, epilepsy, visual impairment, auditory impairment, coma, severe aphasia were excluded in the study.

Data Collection Tool and Procedure

To collect socio-demographic information, a structured questionnaire was prepared for an interview. Three qualified physiotherapists and two supervisors gathered the information. All study participants were asked to provide written consent and were interviewed about their sociodemographic information. Cognitive impairment was assessed using the Montreal cognitive assessment basic (MOCAB).^33,34 The patients medical record has been reviewed to gather medical and clinical information about the patient. The questionnaire was written in English and translated into Amharic; to ensure consistency, the meaning of the Amharic was translated back into English.

Data Management and Quality Control

Data collectors and supervisors were trained to ensure data quality. The data tools were pre-tested prior to data collection to ensure response accuracy, language clarity, and tool appropriateness. The study was piloted on 5% of the total sample size (21 subjects). It was completed within a week of the actual data collection period for the population at Tibebegion specialized hospital, which has similar characteristics to the population chosen for the actual study. Based on the results of the pre-test, the necessary changes were made for the actual study. The supervisor conducts routine checks to ensure that the data is complete and consistent.

Data Processing and Statistical Analysis

Epi info version 7 was used to enter data, and SPSS version 22 was used to analyze it. Bi-variable logistic regressions analysis was employed to show the relationship between dependent and independent variables. To account for confounder of variables found to be associated with cognitive impairment were modeled using multivariate logistic regression. All possible predictors which were significant in the bivariate analysis (p-value <0.25) were included in the multivariable logistic model. The chi-square test was checked to interpret the possible differences in the categorical variables based on cognitive impairment. The Hosmer-Lemeshow goodness-of-fit test was used to assess the fitness of the model. Multicollinearity among the explanatory variables was checked using Variance Inflation Factor (VIF >10). The AOR calculated using back ward step wise multivariate logistic regression. Finally, an AOR was used with a 95% confidence interval and p-value of less than 0.05 was considered statistically significant. The results of study analysis were presented in descriptive statistics, frequency tables, graphs, percentages, means, and standard deviations.

Result

Socio Demographic Characteristics, Medical Conditions and Behavioral Factors

The study included a total of 422 participants, with a 100% response rate. The majority of respondents 274 (64.9%) were male, regarding marital status 345 (81.8%) were married, on the occupation aspect 204 (48.3%) were retired and the average age of study participants was 68 (SD = 8.02). Most of the participants 274 (64.9%) had recurrent type of stroke and 261 (61.8%) had hemorrhagic. Most of participants (299, 70.9%) were hypertensive. Twenty participants (4.7%) were excessive alcohol consumer and 10 (2.3%) were smoking cigarettes daily (Table 1). In terms of duration since stroke was happened most participants (35.8%) were between 3 and 6 month, <3 month (32.7%), >6 month (31.5%), respectively (Figure 1).

Table 1 Socio-Demographic Characteristics, Behavioral Factors and Clinical Conditions of Study Participants at UOGCSH, FHCSH and DCSH Amhara Region Ethiopia 2022 (n = 422)

Figure 1 Time after stroke.

Prevalence of Cognitive Impairment Among Stroke Survivors

In this study, the overall prevalence of cognitive impairment among stroke survivors was 58.3% (95% CI 53.4–63.0%). Cognitive impairment was found in 53.6% of males and 66.7% of females. The prevalence of cognitive impairment among elder populations was 70.10%.The 65.1% in the urban residence, 58.6% among married, 84.7% in the retired population, and 76.7% among illiterates (Table 2).

Table 2 The Prevalence of Cognitive Impairment of Study Participants Among Different Variables at UOGCSH, FHCSH and DCSH Amhara Region Ethiopia 2022 (n = 422)

Factors Associated with Cognitive Impairment Among Stroke Survivors

Explanatory Variables with a significant association in bivariate logistic regression (p 0.25) were fitted to multivariate logistic regression analysis. After considering possible confounders of the variables like age, hypertension, illiteracy, dominant hemisphere lesion, time after stroke, and time in hospital were all found to be significantly associated with cognitive impairment in stroke survivors (p 0.05). In multivariable regression, variables such as stroke history, diabetes, and type of stroke were not significantly associated (Table 3).

Table 3 Factors Associated with Cognitive Impairment in Bivariate and Multivariate Logistic Regression Analysis of Study Participants at UOGCSH, FHCSH and DCSH Amhara Region Ethiopia 2022 (n = 422)

Discussion

The purpose of this study was to determine the prevalence of cognitive impairment and associated factors among stroke survivors attending comprehensive specialized hospitals in Ethiopia’s Amhara region. According to the findings of this study, the overall prevalence of cognitive impairment among stroke survivors was 58.3% (95% CI 53.4–63.0%). This study in line favorably to studies conducted Singapore (54.5%),¹⁴ Uganda (63%)¹⁶ and Ireland (56.6%).³⁵ The possible reason for this could be similarity in age of study participants with comparable sample size and methodology used in Ireland study. Uganda’s study was cross-sectional study with comparable age group and most of socio-demographic characteristics of participants are nearly similar. Also, Singapore’s study was done on same setting (institutional; hospital-based study) and with comparable time since stroke onset of study participants with both types of strokes.

However, this study was more extensive than the one conducted in France (16.3%),³⁶ Egypt (25.3%)³⁷ and China (39.4%).³⁸ The possible reason for this difference could be participants were first ever stroke with different in methodology (prospective study) and difference in educational status of the study participants were attending at least primary education in France study. The difference in Egypt study could be due to difference in time after stroke; most of the participants were acute stroke patients (<3 moths). China's study was follow-up and first ever ischemic stroke age from 14 to 45 years and also most of study participants were literate individuals which might bring a difference in prevalence to our study findings.

The finding of this study was higher than studies in Chile (39%)³⁹ and Ghana (50%).⁴⁰ The reason for this difference could be in methodology and study participants were at least three months after stroke with small sample size (147 participants) in Ghana study which was different from this study. In Chile's study, the difference could be due to differences in socio-demographic characteristics of study participants.

On the other hand, this study was lower than study done in China (80%);²⁷ and Indonesia (68.2%).⁴ The possible explanation for this difference could be in China’s study setting which is community based whereas our study setting is institutional based (hospitals) and study participants were older individuals (age >55) but in our study all adult stroke survivors were included. The possible reason for Indonesia’s study could be difference in stroke type included which is ischemic type only but in our study participants with all types of strokes were included.

This study found that hypertensive people were 7.5 times more likely to develop cognitive impairment than non-hypertensive people, which was supported by research from Malaysia⁴¹ and China.²⁷ Hypertension may cause vascular changes that lead to cognitive impairment by causing hypoperfusion, ischemic and hemorrhagic stroke, and white matter injury.^42,43

The odds of developing cognitive impairment in Participants whose Age 73 years and above were 7.1 more likely compared with stroke survivors age between 18 and 45 years. This was supported by studies done in Egypt,³⁷ Ghana⁴⁰ and Nigeria.⁴⁴ The cause could be due to the nature of stroke, which hastens cognitive decline with age.⁴⁵

The likelihood of developing cognitive impairment in illiterate stroke survivors was 7.0 times greater than in educated >6 years. It was supported by the results of the study conducted in Nigerian⁴⁴ as well as China.²⁷ One possible explanation is that education reduces the negative effects of severe white matter lesions (which cause severe cognitive impairment).⁴⁶ Another reason could be that higher education provides good dynamic-based cognitive stimulation and is effective in improving cognitive performance.⁴⁷

The odd of developing cognitive impairment after stroke in time between before 3 months were 4.8 times more likely when compared with greater than 6 months, which was supported by a study done in Croatia.⁴⁸ The possible reason could be the recovery of the entire structure which controls cognitive function and run fast after stroke needs long period of time.^49,50 Participants with less than three months were more likely to develop cognitive impairment than those with more than three months. That could be one of the reasons. Even though it may persist, cognitive impairment is a major concern during the acute phase of a stroke, with more than half of all stroke survivors experiencing some form of long-term cognitive deficit.³⁵

The odd of developing cognitive impairment in those who were admitted to hospital after 24 hours of the onset of stroke were 4.3 times more likely when compared with those early admission (before 6hrs) to hospitals, which was supported by the study done in Indonesia.⁴ The reason for this could be due to the fact that late onset of hospital admission may increase the number of structures and area of lesson in the brain, because large infarctions are expected to cause more cognitive impairment than small infarctions.

Participants with dominant hemisphere lesion involvement were 4.8 times more likely to develop cognitive impairment than participants with non-dominant hemisphere lesion. This finding was supported by a study conducted in Egypt.⁵¹ One possible explanation is that hemispheric dominance involvement was more common in patients with cognitive impairment. This could be because intelligence or cognitive efficiency is heavily reliant on the accuracy of language processing and hemispheric dominance.^51,52

Conclusion

Cognitive impairment was found to be relatively common among stroke survivors in this study. More than half of stroke survivors who visited comprehensive specialized hospitals in the Amhara region during the study period were found to have cognitive impairment. Age, hypertension, arriving at the hospital after 24 hours, less than three months after stroke, dominant hemisphere lesion, and illiteracy were all significant factors in cognitive impairment. It is preferable that health-care providers and caregivers focus their attention on the elderly, hypertensive patients with acute stroke and dominant hemisphere lesion who are later admitted to the hospital, and non-educated stroke survivors. According to the findings of this study, they were more likely to develop cognitive impairment.

Strength and Limitation of the Study

The multicentered-cross sectional study used in this study was one of its strengths; all types of stroke survivors were included, and the study’s findings identified common factors for cognitive impairment in stroke survivors. Implications for health-care practitioners include educating elderly patients on possible methods of preventing recurrent strokes and controlling hypertension. Furthermore, researchers should conduct a prospective study in order to gather more evidence demonstrating the temporal relationship.

Undiagnosed mental illnesses could have influenced the study subjects’ performance on the MOCAB items, and thus their overall score, as one of the study’s limitations. Because it is a cross-sectional study, it cannot determine the temporal relationship and does not show a strong association of causes and effects.