Comparison of end-of-survival below-knee and above-knee amputations with demographic, comorbidity and hematological parameters

doi:10.21203/rs.3.rs-2507956/v1

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Comparison of end-of-survival below-knee and above-knee amputations with demographic, comorbidity and hematological parameters

https://doi.org/10.21203/rs.3.rs-2507956/v1

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published 13 Jun, 2023

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Introduction: In this study, it was aimed to establish mortality predictive parameters with a higher contribution to mortality by comparing the demographic data, comorbid factors and hematological values of patients who underwent below-knee and above-knee amputation at the end of survival.

Materials and Methods: Eighty-seven patients who were amputated with the diagnosis of diabetic foot between March 2014 and January 2022 and resulted in mortality due to natural causes during follow-up were included in the study. Those who were amputated below the knee were named Group 1 (50 patients), and those who were amputated above the knee were named Group 2 (37 patients). The patients' age, gender, side, comorbid diseases, ASA score, anesthesia type, time to surgery, total hospital stay, CCI (Charlson comorbidity index), ex time and hematological values at the time of first admission were compared in both groups and statistical analysis was performed.

Results: Group 1 and Group 2 had similar distribution in terms of age, gender, side of operation, number of comorbid diseases, time to surgery and CCI (p>0.05). Group 2's mean ASA score, rate of admission to general anesthesia, total hospital stay and crp level were statistically higher than Group 1 (p<0.05). Ex time, albumin value and HgA1c level were statistically lower in Group 2 compared to Group 1 (p<0.05). There was no significant difference in hemogram, wbc, % lymphocyte, % neutrophil, creatinine and Na values of both groups at the time of first application (p>0.05).

Conclusions: It was seen that high ASA score, low albumin value and high crp value were significant predictors of high mortality. Creatinine level and HgA1c value were quite unsuccessful in predicting mortality.

Levels of evidence: Level 3, Retrospective comparative study

Above-knee amputation

Below-knee amputation

Diabetic foot

Mortality predictive parameters

The number of patients diagnosed with diabetes mellitus continues to increase due to the increasing population. In these patients, diabetes can result in outpatient gangrene either alone or with the effect of comorbid diseases. While amputation is seen at least 5.8 percent in the general population, this rate is at least 46.1 percent in diabetic patients. In addition, the survival after amputation is quite short (1–3).

Amputation from the most distal level, where vascular flow and vitality is present, is preferred in order to minimize energy consumption and to make mobilization more convenient. While debridement or minor amputation is applied to 74.8 percent of patients with diabetic foot, 20.3 percent need below-knee amputation and 6.9 percent need above-knee amputation (4, 5).

Due to the ongoing chronic treatment of these patients, mortality is observed with the emergence of other organ failures as well as amputation revisions. When we look at the literature, we see that many hematological parameters and mortality indices have been tested and predictive values have been revealed (6–9). However, studies on the evaluation of patients whose survival has ended seem rather limited.

In this study, it was aimed to create mortality predictive parameters that have a higher contribution to mortality by comparing the demographic data, comorbid factors and hematological values of patients who underwent below-knee and above-knee amputation at the end of their survival.

Between March 2014 and January 2022, 122 patients who developed foot gangrene due to chronic diabetes and underwent below-knee or above-knee amputation were evaluated retrospectively. Local ethics committee approval was obtained (KAEK/2021.01.3).

Patients with unilateral gangrene, who were amputated directly below or above the knee, and whose survival was ended (ex) were included in the study. Patients with previous history of operation or revision history (except debridement) were not included in the study. Bilateral amputations, patients still alive, and amputations due to peripheral arterial insufficiency other than diabetes were excluded from the study. Deaths from causes other than comorbid diseases or Covid-19 were excluded as the cause of ex. Only natural deaths (National death notification system) were included in the study.

The number of patients included in the study was determined as 87. Patients who were amputated below the knee were named Group 1 (50 patients), and patients who were amputated above the knee were named Group 2 (37 patients).

When all patients apply to the emergency or polyclinic, the decision to be admitted to the service is taken and preparations for the operation are started. For level determination, the opinion of cardiovascular surgery (CVS) is taken. The most distal level of flow is determined by the CVS with doppler ultrasound, and a recommendation for a level such as heel protective, Syme, below-knee or above-knee is indicated. When the patients whose surgical preparations are completed, the operation is started by the orthopedist at this level and if there is appropriate vitality, the level is maintained, but if the muscle vitality and contractility are insufficient, the upper level is raised. Treatments for post-operative comorbid diseases are arranged by other clinicians and he is discharged to come for controls after blood glucose regulation is ensured. Patients who are not weak of their outpatient follow-ups are mobilized with a prosthesis. Patients who do not develop wound problems are excluded from follow-up.

Age, gender, operation side, comorbid diseases, ASA (American Society of Anesthesiology) score, anesthesia type, time to surgery, total hospital stay, Charlson comorbidity index (CCI) and ex time data of all patients were collected. Hemogram (hmg), wbc (White Blood Cell), % lymphocyte, % neutrophil, albumin, creatinine, sodium (Na), HbA1c and C-reactive protein (crp) values were collected in the first application.

All operations were performed by surgeons following the same protocol, using the same techniques and methods. All data were collected by the responsible surgeon.

Statistical analysis;

IBM SPSS Statistics 26 (IBM, Chicago, IL, USA) program was used for statistical analysis. Explanatory statistics (mean, standard deviation, median, frequency, ratio, range) and data distribution were evaluated with the Shapiro-Wilk test. Student's t test was used to compare the data distributed between the two groups. p < 0.05 was taken for statistical significance level in all analyzes.

The mean age of Group 1 was 70.9 ± 6.9 (60–89), while the mean age of Group 2 was 74 ± 8.7 (65–98). While the male/female ratio in Group 1 was 1.7, it was 1.8 in Group 2. It had a statistically similar distribution in terms of age, gender, operation side and number of comorbid diseases (p < 0.05). (Table I)

While the mean ASA score was 2.9 in Group 1, it was 3.2 in Group 2. The ASA score average of Group 2 was statistically higher than Group 1 (p = 0.033). Considering the type of anesthesia, a higher number of general anesthesia was used in Group 2 compared to Group 1 (p = 0.0001). (Table I)

Time to surgery had a similar distribution in both groups, but overall hospital stay was higher in Group 2 (p = 0.048). The mean CCI value in Group 1 was 6.2 ± 1.7 (3–10), while the mean CCI value in Group 2 was 6 ± 1.4 (3–9) and both groups had a similar distribution (p = 0.413). The mortality of Group 2 was higher when the ex time was compared (p = 0.034). (Table I)

When the hematological parameters at the first admission were evaluated, there was no significant difference in terms of hemogram, wbc, % lymphocyte, % neutrophil, creatinine and Na values of both groups (p > 0.05). (Table II)

The mean albumin value of Group 2 was lower than Group 1 (p = 0.03). The mean crp value was found to be higher in Group 2 (p = 0.02). The mean HbA1c value was lower in Group 2 (p = 0.018). (Table II)

We found that above-knee amputations have a shorter survival than below-knee amputations. When we compared the demographic, comorbid and hematological values of both groups, it was revealed that age, gender, side, number of comorbid diseases, time to surgery and CCI and hmg, wbc, % lymphocyte, % neutrophil, creatinine and Na values at the time of first admission did not make a significant predictive difference in the mortality criterion. It was revealed that high ASA score, preference for general anesthesia, high total hospital stay, low albumin level at first admission and high Crp level resulted in higher mortality. Although the HbA1c value was low, its occurrence in the group with high mortality meant that it was not associated with mortality.

Some publications state that older age and male gender are more mortal (6, 7). In our study, the mean age of the patients was 70.9 in Group 1, 74 in Group 2, and male gender was dominant in both groups. Although the age and gender distribution of both groups were similar, Group 2 had a more mortal course.

While there are publications stating that mortality increases as the number of comorbid diseases increases (8, 9), our study also revealed that although the number of comorbid diseases in both groups was equal, those who underwent above-knee amputation were more mortal. Although mortality was high in both groups, the reason why Group 2 was more mortal than Group 1 may be related to the stage of the diseases rather than the number of comorbid diseases.

The ASA score is a parameter that indicates the perioperatif anesthetic risk of the patients, and they routinely evaluate the patients' cardiological (echocardiogram), pulmonary (respiratory function test and blood gas) and internal medicine (liver and kidney function tests, electrolyte, hormone) evaluations and give scores in a transparent way. We have revealed that an increase in this score is an important factor that determines the survival of the patient. When we look at the literature, we see that the survival relationship with ASA is also established in other diseases (10). Considering the type of anesthesia, we see that as the ASA score increases, the preference of general anesthesia over regional anesthesia increases. We believe that general anesthesia is preferred for stabilization of patients who are likely to need intensive care after the operation.

After the operation, patients are discharged after consultation with the relevant clinics and stabilization of their chronic diseases. We see that mortality is higher in patients with increased duration. We are of the opinion that the risk of mortality will increase as the stabilization of the problems caused by hemodynamic and comorbid diseases is prolonged.

If the CCI is > 5, the mortality risk is stated as 22.3% in some publication (11). While the CCI was 6.2 in Group 1, it had a mean of 6 in Group 2. Group 1 resulted in a mortality of approximately 2 years on average, and Group 2 with an average mortality of approximately 1 year. It can be said that a high mortality rate of 5 or more is predicted, but although both groups were similar in our study, the more mortal course of Group 2 alone could not constitute a high predictive factor.

Hemogram, wbc, % lymphocyte, % neutrophil, Na and creatinine were similar in 2 groups suggesting that they are not predictors of high mortality. Although low hemogram level was also shown as a mortality indicator (9), it did not make a significant difference in our study. However, the mean hemogram value in both groups (Group 1 hmg:10/Group 2 hmg:9.5) was under normal values. Many publications have suggested that high creatinine level and dialysis dependence are associated with higher mortality (6–9). In our study, while the mean creatinine level in Group 1 was 1.6, it was 1.4 in Group 2. While 15 patients in Group 1 were receiving dialysis, 5 patients in Group 2 were receiving dialysis. It seems very difficult to claim that creatinine level has an effect on mortality. Although we cannot claim that it did not contribute to mortality, as our CCI result was similar in both groups, we can only say that it is not the main factor that makes a difference in mortality.

According to our study, low albumin value causes a more mortal course. If we consider low albumin as a sign of liver failure, it can be argued that liver problems cause a more mortal course than kidney diseases (high creatinine level). There are publications in the literature supporting that low albumin increases mortality (12, 13).

We have seen that the high level of crp also causes a more mortal course. It can be easily said that the extent of septicemia of the process and the strength of the patient's immune system affect mortality. In the literature, it has been stated that resistant bacteria cause a more mortal course (8). It has been stated that crp may also be a predictor of high mortality in terms of mortality (12). The etiology of high crp can be evaluated as septicemia.

Although the HbA1c level was low in Group 2, the high mortality rate indicates that systemic organ damage caused by chronic glucose elevation is more important than HbA1c. However, although there are publications in the literature (14, 15) stating that high HbA1c increases mortality, it is a parameter that can provide a low course of HbA1c with a good treatment and diet.

When we look at some mortality predictive studies, many parameters such as functional status, steroid use, delirium, thrombocythemia, insulin use, and heart diseases were evaluated and they claimed that these parameters also contributed to mortality (6–9). We did not evaluate these parameters in our study, but we consider these parameters as parameters that can be stabilized, since we have shown the necessary care to obtain support from related branches for the stabilization of additional diseases.

There are some limitations of our study. First of all, it is not known that it is retrospective and how much regular care some neurological, personal care and chronic diseases receive in the postoperative period. The standardization of the stability of chronic diseases of patients after discharge period will yield clearer results. Again, these patients could have been included in the study by controlling their hematological evaluations at certain periods.

Although advanced age, male gender, multiple comorbid diseases, high ASA score, high CCI value, low hemogram value, low albumin value and high crp can be associated with mortality in diabetic gangrene-induced amputations, only high ASA score, low albumin value, and high crp value were found to be a significant predictor of high mortality. Creatinine level and HgA1c value were quite unsuccessful in predicting mortality.

Ethics approval and consent to participate

Approval has been granted by Local Ethics Committee (KAEK/2021.01.3).

Consent for publication

Not applicable.

Availability of data and material

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests.

Funding

Not applicable.

Authors' contributions

CÖH and ND designed the study. CÖH and ND collected and analysed the data. CÖH and ND drafted the article. CÖH and ND critically revised the article for important intellectual content. All authors read and approved the fnal version of the manuscript.

Acknowledgements

Not applicable.

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Table I: Demographic data of patients and key parameters

	Below-knee amputations (Group 1) N = 50	Above-knee amputations (Group 2) N = 37	P value
Age	70,9 ± 6,9 (60-89)	74 ± 8,7 (65-98)	0,077
Gender	M:32 F:18	M:24 F:13	0,934
Operation side	R:24 L:26	R:17 L:20	0,851
Number of comorbid diseases	2,52 ± 1,03 (1-5)	2,48 ± 1,04 (1-4)	0,882
ASA score	ASA 2: 11 ASA 3: 29 ASA 4: 10	ASA 2: 2 ASA 3: 25 ASA 4 :10
Mean ASA score	2,98 ± 0,65 (2-4)	3,21 ± 0,53 (2-4)	0,033*
Anesthesia type	General: 16 Spinal: 34	General: 26 Spinal: 11	0,0001*
Time to surgery (day)	6,7 ± 9,1 (1-60)	6,2 ± 5 (1-30)	0,754
Total hospital stay (day)	13,5 ± 13,4 (1-74)	19,8 ± 20 (3-120)	0,048*
CCI	6,2 ± 1,7 (3-10)	6 ± 1,4 (3-9)	0,413
Ex time (day)	511,9 ± 558,2 (3-1900)	309,6 ± 464,7 (2-1875)	0,034*

Table II: Comparison of hematological parameters at the time of first admission

	Below-knee amputations (Group 1) N = 50	Above-knee amputations (Group 2) N = 37	P value
Hmg	10 ± 2,3 (4,5-18,7)	9,5 ± 1,2 (6,3-12,25)	0,231
Wbc (count, thousand cells/mm3)	13,4 ± 7,6 (3,3-39,8)	14,1 ± 7,1 (2,9-39,6)	0,628
% lenfosit	14,8 ± 7,9 (2,4-31,8)	12,2 ± 7,5 (2-39,8)	0,120
% nötrofil	75,4 ± 10,6 (50,6-92,2)	78,5 ± 11,7 (42,2-95,5)	0,195
Albumin	2,8 ± 0,5 (1,8-4,2)	2,6 ± 0,5 (1,5-4,5)	0,03*
Creatinine	1,6 ± 1,4 (0,3-6,9)	1,4 ± 1,2 (0,3-5,1)	0,488
Na	137,4 ± 4,9 (127-156)	137,1 ± 5,6 (128-153)	0,843
HbA1c	7,4 ± 1,5 (5-12,6)	6,7 ± 1,5 (5-11,3)	0,018*
Crp	105,6 ± 91,3 (3-361)	167,7 ± 107,2 (24-415)	0,002*

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Journal Publication

published 13 Jun, 2023

Read the published version in Journal of Foot and Ankle Research →

Editorial decision: Minor revision
20 Apr, 2023
Reviewers invited by journal
13 Apr, 2023
Reviewers agreed at journal
14 Feb, 2023
Editor assigned by journal
29 Jan, 2023
First submitted to journal
25 Jan, 2023

You are reading this latest preprint version

Comparison of end-of-survival below-knee and above-knee amputations with demographic, comorbidity and hematological parameters

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