Authors: Medhanit Melese, Simeneh Mola, Mesay Milkias, Hailemariam Getachew
Categories: Research, Geriatrics, Montreal Cognitive Assessment, Postoperative cognitive dysfunction, Surgery
Source: BMC Geriatrics
Authors: Medhanit Melese, Simeneh Mola, Mesay Milkias, Hailemariam Getachew
The geriatric population is the fastest-growing age group and accounts for one-third of surgical patients. A growing body of evidence reveals that postoperative cognitive dysfunction (POCD) is the most common complication among older surgical patients. However, there is a wide variation in incidence and independent predictors globally. Furthermore, there is a lack of evidence in sub-Saharan Africa, including Ethiopia.
To assess the incidence and predictors of postoperative cognitive dysfunction among geriatric patients undergoing elective surgery in selected governmental hospitals in southern Ethiopia, from February 2023 to October 2023 G.C.
A multi-center, single-arm prospective cohort study was conducted in selected governmental hospitals on patients aged ≥ 60 years. Binary logistic regression was used to assess the relationship between dependent and independent variables, with a p-value < 0.05 considered statistically significant. Crude and adjusted odds ratios with 95% confidence intervals (CI) were calculated to determine the strength of association. The mean differences between preoperative and postoperative cognitive statuses at each follow-up day were analyzed using repeated measures ANOVA.
The overall incidence of postoperative cognitive dysfunction was 46.5%. The trend in incidence showed a gradual decrease in the mean Montreal Cognitive Assessment (MoCA) score from the 3rd postoperative day to the 30th day [Preoperative: 25.94 ± 2.884; 3rd 24.18 ± 3.9; 7th 24.84 ± 3.62; 30th 25.23 ± 3.561; p < 0.0001; large effect size (Partial Eta Squared (ηp²) = 0.98)]. Factors significantly associated with POCD (p < 0.05) included age, ASA III classification, female gender, major surgeries, frailty, preoperative depression, type of anesthesia, intraoperative hypotension and blood loss, and duration of surgery and anesthesia.
This study found a substantial incidence of postoperative cognitive dysfunction in geriatric patients undergoing elective surgery. The findings highlight the complexity of POCD and the wide range of contributing factors. Healthcare providers should include cognitive assessments as part of a holistic approach to patient care, particularly for those at risk of POCD.
The online version contains supplementary material available at 10.1186/s12877-026-07320-1.
Aging is a universal and progressive physiological process characterized by changes in organ and tissue structure, as well as functional status [1]. Due to physiological, pharmacokinetic, and pharmacodynamic changes brought on by aging, patients over 60 are more likely to develop postoperative cognitive dysfunction (POCD) [2]. These changes can lead to increased sensitivity and vulnerability to the effects of surgical procedures, anesthetic drugs, and other medications administered before, during, and after surgery all of which are known to adversely impact cognitive function [3].
Postoperative cognitive dysfunction is typically defined as a decline in cognitive function that occurs in patients following surgery, as measured by comparing their postoperative cognitive status with their preoperative status. It is often diagnosed in the first few days to weeks after surgery [4]. However, some studies have examined longer-term cognitive changes that may persist beyond the immediate recovery period [5, 6]. POCD is a common postoperative brain complication in geriatrics population with worldwide incidence range between 10 and 54% in the first several weeks following surgery [7–9].
The exact mechanisms of POCD are not yet fully understood but are thought to involve a combination of factors, including systemic and neuroinflammation, oxidative stress, neurotransmitter imbalances, anesthesia-related effects, cerebral hypoperfusion, and individual susceptibility [7, 8]. Currently, researchers believe that POCD results from a complex interaction between the vulnerable brains of at-risk patients and the physiological stress and inflammation caused by surgery and anesthesia [7, 9].
POCD exhibit varying degrees of symptoms. While some patients may notice mild variations, others may experience many aspects of the disorder and present in a severe manner, like difficulty recalling and remembering things, incapacity to finish things, inability to keep up with crosswords and reading Combining tasks, multitasking, Decreased psychomotor abilities, difficulties with language comprehension social integration issues [10].
Numerous risk factors have been associated with the development of POCD. These include advanced age, lower levels of education, preexisting cognitive impairment, the type and duration of surgery, type of anesthesia, and various comorbidities. Although POCD can occur in individuals of any age, it is more commonly seen in the elderly [4, 11, 12].
The impact of POCD extends beyond immediate cognitive decline, potentially leading to prolonged hospitalization, increased healthcare costs, reduced quality of life, and added psychological stress for both patients and their families [13]. Individuals with cognitive impairments frequently face additional psychological and social challenges such as stigma, dependence, and discrimination. POCD not only affects patients but also burdens caregivers, families, and the community at large [14].
POCD has been associated with increased healthcare utilization and functional decline during hospitalization. Compared to patients without POCD, those with the condition were more likely to have longer hospital stays (11 days vs. 8 days; p = 0.01) and incur higher medical expenses (5,913.62 USD; p < 0.001) [15].
Despite extensive research, the precise mechanisms and risk factors underlying POCD are not fully elucidated. This knowledge gap continues to hinder the development of effective prevention and intervention strategies [10]. Educational level has consistently been identified as a predictor of POCD, and given that Ethiopia has a high rate of illiteracy and limited access to education, this factor may be particularly relevant in the local context [16].
Therefore, due to sociodemographic differences and a lack of local studies, it is difficult to generalize findings from other regions. Moreover, our literature review found no published studies on postoperative cognitive dysfunction in Ethiopia. Thus, the purpose of this study is to assess the incidence and predictors of postoperative cognitive dysfunction in geriatric patients undergoing elective surgery.
A multi-center, single-arm cohort study was conducted from June 2023 to August 2023 at Hawassa University Comprehensive Specialized Hospital, Adare General Hospital, and Dilla University Teaching Hospital, with a follow-up duration of one month. Ethical clearance was obtained from the institutional review board under protocol unique number duirb/031/23 − 05.
Patients aged over 60 years who were scheduled for elective surgery during the study period and willing to participate were included in the study at the selected hospitals in southern Ethiopia.
Patients were excluded if they were undergoing cardiac or neurosurgical procedures; had pre-existing severe cognitive dysfunction; had a diagnosis or history of psychiatric disorders; had severe auditory (i.e., almost complete or total inability to hear any sounds) or visual disabilities; or had a history of cardiac surgery within the past year.
To determine the sample size, the finite population formula by Taro Yamane was used [17]. Based on the surgical logbooks of the three hospitals, a total of 195 geriatric surgical patients were expected during the three-month study period. Where: signifies the sample size, N: signifies the population under study, signifies the margin error. n = N/ 1 + N (e)2.
N = 195 e = 0.05; e2 = 0.025 n = 195/1 + 195(0.025)2 n = 131 after adding a 10% contingency for non-response, the final sample size was 144 geriatric surgical patients.
A situational analysis was conducted using surgical logbook records of geriatric surgeries over six months (December 2021 – May 2022) from each hospital. Based on this review, 100 geriatric surgeries were recorded at Adare General Hospital (AGH), 90 at Dilla University General Hospital (DUGH), and 300 at Hawassa University Comprehensive Specialized Hospital (HUCSH). The sample was proportionally allocated to each hospital according to their average three-month surgical volume.
During the study period, data were collected using systematic random sampling from the daily operating room schedule lists. A sampling interval of every third patient (3:1 ratio) was applied to select participants.
This prospective single-arm cohort study was conducted across three hospitals with support from 12 trained data collectors and 2 supervisors. Study information was translated into Amharic and shared with participants before obtaining written informed consent.
Data were collected through chart reviews, interviews, and validated psychometric tools. Baseline cognitive function was assessed one day preoperatively using the Amharic version of the Montreal Cognitive Assessment (MoCA), which was previously validated in Ethiopia (inter-rater reliability = 0.96, Cronbach’s alpha = 0.79) [16]. Depression and frailty were assessed using the DIS short form and the Fried Frailty Scale, respectively.
Patient demographics, medical history, and surgical details were collected from charts and interviews. Postoperative data included pain scores (on postoperative day 3), length of hospital stay, and follow-up MoCA assessments conducted on postoperative day 3, day 7, and day 30 either in-hospital or via home visits.
POCD was defined as a decline of ≥ 2 standard deviations from the preoperative MoCA score.
Frailty is assessed using the Fried criteria, which considers factors like significant weight loss within the past year, feelings of exhaustion, and low levels of physical activity, poor gait speed, and weak grip strength. The presence of three features indicates frailty, one to two features indicate intermediate frailty, and no features suggest non-frailty [18].
The Montreal Cognitive Assessment screening Tool (MoCA) is a concise, one-page cognitive screening scale consisting of 30 points and typically takes around 10 min to administer. A score of 26 is used as a cutoff to distinguish between different preoperative cognitive normal cognitive function, mild cognitive dysfunction, and severe cognitive dysfunction. normal (MoCA scores ≥ 26), mild cognitive dysfunction (20 ≤ MoCA scores < 26), and severe cognitive dysfunction (MoCA scores < 20) [16].
Postoperative cognitive dysfunction refers to a decline in performance on neuropsychiatric tests that becomes noticeable days to weeks after surgery. It is defined as a postoperative reduction in cognitive function of at least 2 standard deviations from the preoperative MoCA score [19].
The Geriatric Depression scale is a self-report tool used to assess depression in older adults. Respondents answer 15 questions with “Yes” or “No,” and a score greater than 5 indicates the presence of depression when questions are answered negatively [20].
Assessed at post-operative 3rd day according to numeric rating scales (NRS), 1–3 was classified as mild pain, 4–6 as moderate, and 7–10 as severe [21].
Once data were collected, they were entered into EpiData version 4.6 and then exported to IBM SPSS Statistics version 26 for analysis. The data analysis included both descriptive and inferential statistics. Qualitative variables were summarized using frequencies and percentages, while quantitative variables were described using means and standard deviations (SD).
Normality was assessed using the Kolmogorov–Smirnov test, and outliers were examined using both graphical and non-graphical methods. Bivariate analysis was performed using binary logistic regression.
Both bivariate and multivariable logistic regression analyses were conducted. In the bivariate analysis, variables with a p-value < 0.25 were considered candidates for inclusion in the multivariable logistic regression model.
The results of the multivariable analysis were reported as adjusted odds ratios (AORs) with corresponding 95% confidence intervals (CIs). Variables were considered significantly associated with postoperative cognitive dysfunction (POCD) if the p-value was < 0.05. Multicollinearity was assessed using the variance inflation factor (VIF), with a VIF > 10 indicating multicollinearity.
The strength of association was evaluated using both crude and adjusted odds ratios along with their respective 95% confidence intervals. Missing data and loss to follow-up were addressed through complete case analysis under the assumption that data were missing not at random (MNAR).
To analyze repeated measurements, repeated measures ANOVA (Analysis of Variance) was applied. The goodness-of-fit of the final model was assessed using the Hosmer–Lemeshow test, where a p-value > 0.05 indicated an adequate model fit.
The study received a support letter and ethical clearance from the Institutional Research Ethical Review Board (IRB) of Dilla University College of Health Sciences and Medicine under protocol unique number duirb/031/23 − 05. The purpose and significance of the research were clearly explained to participants, and written informed consent was obtained by the data collectors.
To maintain confidentiality, no identifying information was recorded; instead, codes were used to represent participants. Participation was entirely voluntary, and individuals were free to withdraw from the study at any time without consequence.
The study adhered to the ethical principles outlined in the Declaration of Helsinki for research involving human subjects and reported its findings in accordance with the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) checklist.
A total of 144 patients were enrolled. The response rate for the 3rd postoperative day cognitive assessment was 100%, as all participants were available. Three participants died before the 30th day assessment, resulting in a 97.9% response rate (141/144) at that time point. The full sample (N = 144) was used for preoperative, 3rd, and 7th day assessments, while complete case analysis was applied for the 30th day MoCA scores (N = 141).
Among the elderly participants, the majority (73.6%) were male. The mean age of the participants was 71.36 years (SD = 8.85) (Table 1).
Table 1Socio-demographic characteristics of study participants at HUCSH, AGH, DUGH October 2023 (N = 144)VariablesFrequencypercentageSexMale10673.6Female3826.4Age60–70 yrs6444.471–80 yrs5638.9> 80 yrs2416.7Smoking historyYes1510.4No12989.6History of alcohol drinkingYes3020.8No11479.2BMIUnderweight128.3Normal12788.2Overweight53.5Education levelUneducated6545.1Below 6 grade2920.16–12 grade2618.1Above 12 grade2416.7Chronic diseaseYes6444.4No8055.6
As shown by the distribution of preoperative risk factors, the majority of patients were classified as ASA II (120 patients, 83.3%), and approximately 63 patients (43.8%) were categorized as prefrail (Table 2).
Table 2Perioperative variable distribution of study participants at HUCSH, AGH, DUGH October 2023 (N = 144)VariablesFrequencyPercentageASA STATUSASA II12083.3ASA III2416.7SHAPE surgery invasivenessMinor2215.3Intermediate9465.3Major2819.4FrailtyNon-frail4833.3Pre-frail6343.8Frail3322.9Type of anesthesiaGA4833.3RA9666.7Type of surgeryGeneral surgery4229.2Urology6444.4Orthopedics3121.5Gynecology74.9Postoperative pain severityMild1913.2Moderate11579.9Sever106.9
The cumulative incidence of postoperative cognitive dysfunction (POCD) was found to be 46.5% within a one-month period, based on preoperative MoCA scores. The incidence of cognitive dysfunction decreased over time following surgery. Specifically, 67 patients exhibited POCD on the 3rd postoperative day, 41 patients on the 7th day, and 23 patients on the 30th postoperative day (Fig. 1).
Fig. 1Incidence of POCD at 3rd, 7th and 30th days postoperatively
A repeated measures one-way ANOVA with a Greenhouse-Geisser correction was used to determine the difference in the mean MoCA scores across the preoperative and postoperative assessments. The analysis showed a statistically significant difference between the preoperative and postoperative scores on the 3rd, 7th, and 30th days (F(1.544, 432.32) = 54.668, p < 0.0001), with a large effect size (Partial Eta Squared = 0.98).
Post hoc analysis using the Bonferroni correction revealed a statistically significant decrease in MoCA scores at all postoperative assessment points compared to the preoperative baseline. However, the trend among postoperative scores showed a gradual improvement from the 3rd postoperative day to the 30th day [0 day(preoperative) 25.94 ± 2.884, 3rd day 24.18 ± 3.9, 7th day 24.84 ± 3.62, and 30th day 25.23 ± 3.561)] P < 0.0001(Fig. 2) (Table 3).
Fig. 2Mean MoCA score of preoperative, 3rd, 7th and 30th postoperative days’ cognitive assessment
Table 3Associated factors of postoperative cognitive dysfunction (N = 144)VariablePOCD occurredP valueCOR(95% CI)P valueAOR(995%CI)YesNoAge, years 60–7012(18.7)52(81.3)0.0011 71–8037(66.1)19(33.9)8.43 (3.65–19.48) 0.02 8.04(2.87–12.46)* > 8018(75)6(25)13 (4.25–39.72) 0.032 7.95(1.90-13.24)Sex Male37(34.9)69(65.1)0.001 0.00 1 Female30(78.9)8(22.1)7.1(2.9–16.8)2.78(4.14–9.49)Alcohol history Yes28(93.3)2(6.7)0.0026.9(6.1-118.9) 0.00 6.31(5.19–13.34) No39(34.2)75(65.8)11Educational level Uneducated34(52.3)31(47.7)0.0019.50(2.54–35.51) 0.03 3.456(1.056–10.4) Below 6 grade19(65.5)10(34.5)0.0055.48(1.69–17.82)0.700.83(0.21–3.23) 6–12 grade10(38.5)16(61.5)0.093.13(0.82–11.850.560.20(0.05–0.84) Above 12 grade4(16.7)26(83.3)11Comorbidity Yes38(59.4)26(40.6)0.062.57 (1.31–5.05) 0.01 3.74(1.36–10.31)* No29(36.2)51(63.8)11ASA status ASA 248(40)72(60)0.0011 0.008 1 ASA 319(79.2)5(20.8)5.70(1.99–16.308.31(1.74–19.76)**SHAPE surgical complexity Minor9(40.9)13(59.1)11 Intermediate34(36.2)60(63.8)0.6790.82(0.32–2.113)0.100.478(0.13–1.79) Major24(85.7)4(14.3)0.0028.67(2.23–33.68) 0.01 6.94(2.31– 20.84)*Frailty Nonfrial7(14.6)41(85.4)0.0011 Prefrial33(52.4)30(47.6)6.35(1.99–15.96)0.074.30(1.79–11.08)Frial27(81.8)6(18.2)6.44(2.51–16.52) 0.02 5.048(1.8– 13.4)Preoperative depression Yes37(60.7)24(39.3)0.0042.72(1.38–5.38) 0.01 3.65(1.37–9.68) No30(36.1)53(63.9)11Preoperative cognitive statues Normal27(32.5)56(67.5)0.0011 Mild cognitive dysfunction40(65.6)21(34.4)3.95(1.96–7.95) 0.01 4.68(1.56–13.95)Type of anesthesia GA34(72.3)13(27.7)0.004.99(2.32–10.73) 0.001 1.87(1 0.01-2.03) Regional anesthesia33(34.4)63(65.6)11Blood loss, ml < 500 ml31(31.0)69(69.0)0.001 0.007 1 ≥ 500 ml36(81.8)8(18.2)10.01(4.17–24.04)1.005(1.00–1.01)Intraoperative hypotension Yes32(71.1)13(28.9)0.004.50(2.09–9.673) 0.001 1.786(1.47–3.06) No35(35.4)64(64.4)11Duration of surgery < 1 h8(26.7)22(73.3)11 1–2 h25(35.2)46(64.8)0.211.49(0.581–3.84)0.037.69(2.61–22.63) > 2 h34(79.1)9(20.9)10.39(3.48–30.99) 0.000 1.037(1.01–1.06)Duration of anesthesia < 1 h4(66.7)2(33.3)0.2511 1–2 h23(59.0)16(41.0)0.45(0.08–2.581)0.070.12(0.01–3.85) > 2 h47(47.5)52(52.5)1.34(1.05–2.13) 0.001 42.4(4.70–377)
Compared with male patients, female patients had a significantly higher risk of developing postoperative cognitive dysfunction (POCD) (p = 0.000, adjusted odds ratio [AOR] = 2.78, 95% CI: 4.14–9.49). Additionally, patients with no formal education were 3.46 times more likely to develop POCD compared to those with education above grade 12 (p = 0.03, 95% CI: 1.06–10.40) (Fig. 1) (Table 1) (Fig. 3).
Fig. 3Educational statues versus mean MoCA in each follow-up time
Patients classified as ASA III were eight times more likely to develop postoperative cognitive dysfunction (POCD) compared to ASA II patients, with a statistically significant association (p = 0.008, adjusted odds ratio [AOR] = 8.3, 95% CI: 1.74–19.76).
Additionally, age was significantly associated with POCD risk; geriatric patients aged over 80 years had a higher likelihood of developing POCD compared to those aged between 60 and 70 years (p = 0.03, AOR = 7.95, 95% CI: 1.90–13.24)Fig. 4) (Table 3).
Fig. 4Distribution of age in relation to postoperative cognition
Patients with comorbid conditions had a higher incidence of postoperative cognitive dysfunction (POCD) (59.4%) compared to those without any comorbid illnesses (35.8%) (p = 0.01, adjusted odds ratio [AOR] = 3.74, 95% CI: 1.36–10.31).
Similarly, frail patients were 5.04 times more likely to develop POCD than non-frail patients (p = 0.02, AOR = 5.04, 95% CI: 1.80–13.40).
Furthermore, a surgery duration exceeding two hours was significantly associated with POCD (p = 0.00, AOR = 1.03, 95% CI: 1.01–1.06).
Table 3 below summarizes the significant variables identified through both bivariate and multivariate logistic regression analyses.
Data are presented as p value, crude odd ratio as well as adjusted odd ratio with 95% confidence interval POCD, postoperative cognitive dysfunction, * (significant value), ** (very significant value).
In this study, 46.5% of geriatric patients who underwent non-cardiac surgery experienced post-operative cognitive dysfunction (POCD). This incidence rate falls within the globally reported range. According to a meta-analysis by Insa Feinkohl et al. (2017), the global incidence of POCD in older adults during the initial weeks after surgery ranges from 10% to 54% [22].
The incidence of POCD in our study is four times higher than that reported in studies conducted in India. In India, the incidence rates were reported as 12% on day three, 8% on day seven, and 7.5% after 30 days post-surgery. This disparity might be attributed to a substantial difference in the number of patients with no formal education (65 in our study compared to only 8 in the Indian research) [23]. The results of an international multi-center study conducted by Moller Jt and colleagues also indicated that having lower levels of education was identified as a risk factor for the development of early postoperative cognitive dysfunction (POCD) [24].
The incidence of POCD showed a decreasing trend across each follow-up visit, indicating that short-term assessments on postoperative days 3, 7, and 30 revealed a gradual reduction in its occurrence. This observation suggests that POCD may be transient in a subset of patients, while in others, it may persist beyond the 30-day period. The gradual decline over time is consistent with findings from a prospective observational study conducted in India in 2014, which involved 200 patients undergoing elective non-cardiac surgeries [23].
The variance in the incidence between our study (46.5%) and the prospective observational studies conducted by Osman et al. (15%) [25] and Monk et al. (12.7%) [26] can be attributed to differences in the timing of cognitive assessments. These earlier studies assessed the occurrence of POCD over an extended period, specifically within 3 to 6 months after surgery. In contrast, our study focused on evaluating POCD as early as the third day following surgery.
We observed a significant gender-based difference in the occurrence, where women are more likely to develop POCD. These findings are in line with a prospective cohort study conducted by Kotekar and colleagues. One potential explanation for this gender difference is the neuroprotective effect of estrogen. Estrogen is believed to play a protective role in preserving cognitive function, and the decrease in sex steroid hormone levels, particularly after menopause, could be a contributing factor to the higher prevalence and increased severity of conditions such as Alzheimer’s disease (AD) in women as compared to men [27].
One of the noteworthy factors that emerged as significant in our study is preoperative depression. However, it’s important to highlight that a cohort study conducted by Sophia Wang and her team did not observe any correlation between preoperative depression and the occurrence of postoperative cognitive dysfunction (POCD) 3 months after surgery [28]. One potential explanation for this inconsistency could be the difference in the number of depressed patients included in the two studies. In our study, the number of individuals with depression was relatively higher (n = 61 out of 144), whereas in Sophia Wang’s study, the number of depressed patients was lower (n = 16 out of 167). This variation in sample size may have influenced the ability to detect a link between preoperative depression and POCD in the respective studies.
In our study, we found a striking association between a history of alcohol consumption and the development of POCD. Specifically, approximately 97.7% of patients with a history of alcohol use experienced POCD, with a p-value of 0.00. Furthermore, the adjusted odds ratio (AOR) was 6.31, indicating a substantially increased risk. Our findings align with the results of other research studies. A prospective cohort study by Xiaoyue et al. revealed that alcohol consumption was a significant predictor for developing POCD, with an odds ratio of 1.016 and a 95% CI of 1.009 to 1.024 (p < 0.001) [29]. Additionally, Ljiljana G and her team also concluded that alcohol consumption was a substantial risk factor for POCD, with a p-value of 0.001 [30]. These collective findings highlight the consistent evidence that links alcohol consumption to a heightened risk of developing postoperative cognitive dysfunction.
In a prospective observational study conducted in Turkey in 2016, several factors were identified as influencing the occurrence of POCD. These factors comprised older age (P < 0.001), high ASA scores (P = 0.004), the presence of comorbid conditions (P = 0.025), extended surgical durations (P = 0.018), and reduced postoperative hematocrit levels (P = 0.014) [31]. These findings are in line with the results of our own research, except for the observation that postoperative hematocrit levels were not associated with POCD in our analysis. This variation could be attributed to the fact that in our study area, postoperative complete blood count (CBC) tests are not routinely performed unless there is a specific clinical indication.
In comparison to nonfrail patients, our study found that frail patients faced more than a four-fold heightened risk of experiencing postoperative cognitive dysfunction. This observation is consistent with the findings of Partridge and colleagues, who also identified an independent link between frailty and cognitive dysfunction, with an odds ratio of 12.55 (P < 0.001) [32]. Given that geriatric syndromes such as frailty and cognitive dysfunction often coexist, this strong association is unsurprising, although frailty has not been extensively evaluated in most previous studies.
The question of whether the incidence of postoperative cognitive dysfunction differs between regional anesthesia and general anesthesia remains a topic of discussion. In our study, patients who received regional anesthesia had a significantly lower risk of postoperative cognitive dysfunction (p = 0.006, AOR = 0.185). A randomized trial conducted by Rasmussen et al. also observed a tendency toward improved cognitive outcomes one week following the surgery, which aligns with our findings. However, the study revealed that there was no established causal relationship between general anesthesia and long-term postoperative cognitive dysfunction (50). Interestingly, our study did not find a significant difference in the effect of POCD based on the type of induction agent used. In another RCT study done by Li WX, Luo RY et al. (2019), it was shown that of geriatric patients undergoing hip or knee replacement surgery while under spinal anesthesia had a lower incidence (52).
A prospective cohort study conducted by Zhang Y. et al. presents results that differ from our research findings. They reported no significant differences in operation time, bleeding, or transfusion between the groups with postoperative cognitive dysfunction (POCD) and those without POCD [33]. This difference in findings can likely be attributed to the scope and focus of the studies. In our study, we included a diverse range of surgeries with varying levels of bleeding and durations, which can introduce variability in the data. In contrast, Zhang Y. et al.‘s study specifically focused on colorectal surgery, which might have different surgical characteristics and risk factors, leading to distinct results.
The variation in surgical types and patient populations between the studies underscores the importance of considering the specific context and surgical procedures when assessing the risk factors for POCD. Different types of surgeries may have unique risk profiles and contributing factors.
The strengths of this study include the inclusion of elderly surgical patients from diverse surgical specialties across three teaching hospitals in southern Ethiopia, enhancing the generalizability of the findings. The study also achieved a high response rate and is the first of its kind in the region to investigate postoperative cognitive dysfunction (POCD) while accounting for a broad range of potential risk factors.
The limitations of this study include a short follow-up period, which may have prevented the detection of long-term cognitive changes. The relatively small sample size limited the statistical power and reduced the generalizability of the findings. The Repeated use of the MoCA tool may have led to learning bias, underestimating the incidence of POCD over time. The depression and frailty assessment tools, though standardized, were not validated in the Ethiopian context, which may have affected the accuracy of those measurements. Lastly, incomplete postoperative hematocrit data, due to limited CBC testing, restricted the analysis of some relevant clinical variables.
The study found a substantial incidence of POCD, with 46.5% of the geriatric patients experiencing cognitive dysfunction following surgery. This POCD study in the elderly showed a gradual decline in the incidence of POCD from early postoperative day 3, day 7, to1 month after surgery. Several demographic characteristics were identified as predictors for POCD, which include advanced age, female gender, and being uneducated. Also, Patients with history alcohol drinking, depression, preoperative mild cognitive dysfunction, frailty, ASA III classification, and comorbid illness had an increased risk of POCD.
Surgical and anesthesia factors, including major surgeries, longer duration of surgery, and anesthesia, general anesthesia, as well as intraoperative hypotension and blood loss > 500 ml, were also found to be significant risk factors for developing postoperative cognitive dysfunction. These findings underscore the significance of socio-demographic factors, patient clinical status, psychological factors, and surgical and anesthesia factors in cognitive outcomes.
These study findings show the magnitude and complexity of POCD and the diverse significant predictors that may contribute to its development. Understanding these factors is crucial for identifying at-risk patients and providing appropriate care.
We suggest considering comprehensive preoperative assessments, including cognitive function and psychological well-being, to identify patients at higher risk of developing POCD. Further research on long-term and large-scale including preventive strategy should be considered.
Supplementary Material 1.