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  Table of Contents 
Year : 2018  |  Volume : 19  |  Issue : 1  |  Page : 6-10

Abnormal routine preoperative test results and their perioperative anesthetic impact in patients aged 60 years and more: An observational study

1 Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
2 Department of Anaesthesiology, Andaman and Nicobar Islands Institute of Medical Sciences and GB Pant Hospital, Andaman and Nicobar Islands, India

Date of Submission07-Nov-2017
Date of Acceptance18-Feb-2018
Date of Web Publication22-May-2018

Correspondence Address:
Dr. Habib Md Reazaul Karim
Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Raipur - 492 099, Chhattisgarh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/TheIAForum.TheIAForum_41_17

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Background and Aim: Physiology of the human body changes with aging making physicians more inclined toward the use of routine preoperative investigations in the elderly to detect hidden abnormalities. The present study was aimed to assess the prevalence of abnormal test results and their impact on anesthetic management among patients aged 60 years or more.
Methods: This observational study was conducted during December 2016 to April 2017. Data were collected by prospectively screening the files of the patients attending preanesthetic evaluation clinic (PAEC). Demographic parameters, physical status, surgery grade, normal and different abnormal test results, and their impacts were noted. Data were expressed in absolute numbers, percentage scale, and number needed to investigate (NNI). Central tendencies and dispersions were calculated using INSTAT software.
Results: Data from file of 181 patients (mean + standard deviation age 66.69 + 5.89 years; 82 [45.30%] female) were collected. The median American Society of Anesthesiologists physical status was II and 59.67% underwent National Institute of Clinical and Health Excellence Grade 1 surgery. Entire patient attended PAEC with routine investigations done; 125 (69.06%) had at least one abnormality. Out of total 1275 tests done, 241 (18.90%) results were abnormal. Only 27 (11.20%) abnormality had an impact; 21 (77.78%) did not alter preoperative/anesthetic management but led to further testing, unnecessary consultation, and mean 3.84 days delay. The NNI for detecting one significant impact was 255.
Conclusion: Majority of the patients aged 60 years or more were having at least one abnormal test results in routine preoperative tests but had minimal impacts in perioperative anesthetic management. It caused unnecessary further testing, consultation, and delay. Age per se should not be a criterion for ordering routine preoperative testing. The clinical trial registration number was CTRI/2018/01/011235.

Keywords: Abnormality results, elderly, laboratory tests, outcome, preoperative

How to cite this article:
Reazaul Karim HM, Sahoo SK, Prakash A, Rajaram N, Kumar S, Narayan A. Abnormal routine preoperative test results and their perioperative anesthetic impact in patients aged 60 years and more: An observational study. Indian Anaesth Forum 2018;19:6-10

How to cite this URL:
Reazaul Karim HM, Sahoo SK, Prakash A, Rajaram N, Kumar S, Narayan A. Abnormal routine preoperative test results and their perioperative anesthetic impact in patients aged 60 years and more: An observational study. Indian Anaesth Forum [serial online] 2018 [cited 2023 Jun 7];19:6-10. Available from: http://www.theiaforum.org/text.asp?2018/19/1/6/232908

  Introduction Top

Preoperative investigation has been scrutinized from time to time with regard to cost-effectiveness as well as usefulness.[1],[2] The Task Force of the American Society of Anesthesiologists (ASA) and national institute of clinical and health excellence (NICE) recommend against the routine use of preoperative test and state to do investigations with specific clinical indications; age is one such.[3],[4] Despite having negative evidences and recommendations, the practice is still very much prevalent due to many reasons.[5] Age-related physiological change also tempts perioperative caregiver toward ordering such tests to detect hidden abnormalities. The present study was aimed to estimate the prevalence of abnormal laboratory test results and their impact on anesthetic management among the patients aged 60 years or more undergoing elective surgeries.

  Methods Top

With the approval from the Institute Ethics Committee, the present observational, prospective study was conducted in a tertiary care teaching hospital of India during December 2016–April 2017 (Subgroup analysis of CTRI/2018/01/011235). The study was designed with an expected 50% +10% prevalence of at least one abnormal test result among expected participants, which was based on the findings of 3-day pilot survey in the same institute. Online epidemiological tool OpenEpi (Open Source Epidemiologic Statistics for Public Health; http://www.openepi.com/SampleSize/SSPropor.htm) was used for calculating the sample which gave a sample size of 97 for 95% confidence level applicable for a large population. Considering a nonrandomized sampling, a design effect of 1.8 was applied, and a target sample of minimum 175 patients was taken. Files of the patients aged 60 years or more, of either sex attending preanaesthesia evaluation clinic (PAEC) for planned elective surgeries, were screened for data collection. Bedridden or immobile patients whose body weight could not be assessed were excluded from the study. Patients' demographic parameters, grade of surgery as per adapted NICE classification, ASA physical status, etc., were noted. The adapted NICE classification of surgical grades is presented in [Table 1].[4] The results in terms of normal and abnormal tests for all the laboratory investigations performed before the patient was declared fit for proposed surgery after evaluation and risk stratification in the PEAC were noted. Impact of abnormal test results in terms of referral, delay, further investigations, and changes in anesthetic management plan were also noted. An impact was considered to be significant only if that abnormal result led to a change in the perioperative anesthetic management. Hemoglobin level of <12 gm% was noted as anemic in this study. Numbers of newly diagnosed comorbidity (disease) from the investigations were also noted. Numbers of abnormal tests as well as impacts were expressed in absolute number and percentage scale. Number needed to investigate (NNI) for detecting an abnormal test result with a significant impact was also calculated. The NNI was used as synonymous to number needed to treat and calculated using same formula (i.e., 1/ARR, where ARR – absolute risk reduction, which is equal to Intervention Event Rate-Control Event Rate). In the present study having single cohort control, event rate is zero as there is no control group. Hence, NNI becomes 1/intervention event rate or 1/prevalence. High blood pressure or the new diagnosis of hypertension leading to an impact be it significant or not, were not included in the study for analysis as the diagnosis and impact were based on clinical finding (i.e., blood pressure values), not preoperative laboratory test values. Metric data were further analyzed for measuring central tendencies and dispersions using INSTAT software (GraphPad Prism Software, La Jolla, CA, USA). P < 0.05 was considered statistically significant.
Table 1: Adapted National Institute of Clinical and Health Excellence surgical grade

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  Results Top

A total of 181 files of patients, who have completed the PAEC procedure for elective surgeries during the study period, were included in the analysis. The median age of the patients was 65 years with a range of 60–95 years. Ninety-nine (54.70%) patients were male and median ASA physical status was II. The age, sex, ASA physical status classes, and NICE surgical grade-wise distributions are shown in [Table 2].
Table 2: Demographic, physical status, and surgical grade-wise distributions of the cohort (N=181)

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A total of 127 (70.16%) patients were having at least one comorbid medical conditions; 81.10% had either or both cardiorespiratory system involved and arterial hypertension was the most common. The comorbid conditions are noted in [Table 3].
Table 3: Distribution of the comorbid conditions (N=181)

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In an average, seven tests per patient were done as a routine preoperative investigation. One hundred and twenty-six (69.61%) patients had 241 abnormal test results out of the total 1275 tests done [Table 4]. Only 27 (11.20%) abnormal tests had an impact in terms of repeat testing, reporting, consultation, etc., Five (0.392% of the total tests done) abnormalities detected led to a change in the anesthetic management plan which indicated that the NNI to detect one significant abnormal result was 255 (i.e., 1/0.392% = 100/0.392 = 255).
Table 4: Distribution of routine tests done with respective results and impacts

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A total of 116 (9.098%) out of total test results could be regarded as hidden or new and/or hinted a new diagnosis. However, only three (0.235% of the total tests done) actually had a significant impact [Table 5] which indicated that the NNI to detect one significant hidden comorbidity was 425 (i.e., 1/0.235% = 100/0.235 = 425).
Table 5: Distribution of comorbidities detected newly with respective impacts in terms of number needed to investigate

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Ninety-nine (78.57%) patients with abnormal test results were cleared without any further impact. Out of the total 27 impacts, consultation/opinion from physicians was the most common (85.19%), followed by further or repeat testing (11.11%) and reporting (3.70%). Twenty impacts also had delay; 19 resulted in a mean 3.84 days (range 1–11 days) of unnecessary delay.

  Discussion Top

At present, there is a continuous expansion of older population, and so it is the demand of increasing surgical interventions among them. Continuation of traditional practice of routine testing will cost a lot to the health-care delivery. There is no doubt that elderly are a potential candidate to have abnormal laboratory test results and this is proven by the finding of the present study (i.e. 69.09% patients were having at least one abnormal test results). This is definitely a huge number, but the question is, whether these abnormal test results change the perioperative anesthetic management?

Despite 126 patients having at least one abnormality, only 27 (21.43%) patients had to face an impact, and only three (2.44%) patients' perioperative anesthetic management was changed. This indicates that the number of elderly patients 'needed to investigate' routinely for detecting one significant impact from an abnormal test result was 41. This is not at all cost-effective considering the very low anesthesia-related mortality. Analyzing the patterns of preoperative testing from National Surgical Quality Improvement Program database, it was found that neither testing nor abnormal test results were associated with postoperative complications.[6] Even study conducted in patients aged 70 years or more found that abnormal values were not a predictor of postoperative adverse outcomes.[7] Moreover, abnormal test results lead to unnecessary further testing, delay, and referrals and has a very minimal impact on perioperative anesthetic management.[8] Although abnormal test result is one of the reasons behind the cancellation of elective surgery,[9] not all abnormal test results lead to the postponement or cancellation. Another audit showed that only 5 out of 5, 929 (0.084%) surgeries were cancelled on the day of surgery for abnormal test result.[10] In context to very high prevalence of abnormal test results in all age groups, this number, i.e., 0.084% is very insignificant. The present finding also reiterates this. All these seriously questions the routine practice of preoperative testing taking age as sole basis of testing in patients aged 60 years or more. As nearly 92% of the present cohort was ASA II and above, it also indicates that most of such patients are likely to have one or another abnormality. Although the present findings question the credibility of routine testing, it is not indicating that preoperative laboratory testing should not be done at all. Rather, it indirectly indicates that the investigations ordered should be based on history, physical findings, and comorbidity.

Aging is a continuum progressive process occurring at different rates in different individuals having both physiologic as well as pathophysiologic impacts on cardiorespiratory reserve and fitness.[11] This significantly interferes with the function of organs and systems, which in turn is reflected as altered results in the laboratory test.[12] The degree of fitness and performance of a person when coping with health problems depends more on the biological age than chronological age.[13] Biological age is the result of pathophysiologic aging processes, comorbidity, and genetic factors.[13] Therefore, rather than mere depending on chronological age, preoperative assessment and risk stratification should be based on biological age which can probably be assessed clinically by estimating or knowing the cardiopulmonary fitness. This can be assessed and expressed in terms of metabolic equivalents of tasks (METs). The cardiopulmonary fitness or METs can be assessed clinically by simply asking few day-to-day household and recreational activity-related questions and probably few bedside clinical tests.[14],[15]

The present study findings of only 7.73% of ASA physical Class I patients in the present cohort do indicate that aging process and comorbidity are a big factor. However, these conditions are usually controlled as indicated by the findings of more than 55% of the cohort belonging to ASA Class I and II. Moreover, only 4 (2.209%) patients had METs <4 in the current cohort. This also indicates that nearly 98% of the patients aged 60 years and above were having either intermediate or good METs to withstand even major noncardiac surgeries. Even nearly four-fifth of the cases, the invasiveness of surgeries planned was of NICE Grade 1 and 2 (i.e., minor and intermediate), which can even be performed in the patients with relatively low METs.

Although the present study has limitations of being single-center observational study, the findings give us a strong message. Institute-to-institute and person-to-person variation of practice is expected and such study from few other centers or a multicenter study with different geographical and varied population will give us a better insight.

  Conclusion Top

Majority of the patients aged 60 years or more will have at least one abnormal test results in routine preoperative tests but has minimal impacts in perioperative anesthetic management. These abnormalities, however, cause unnecessary further testing, consultation, delay, etc. The NNI to have a significant impact or detecting a hidden comorbidity was very high and cannot be regarded at all as cost-effective.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Fischer SP. Cost-effective preoperative evaluation and testing. Chest 1999;115:96S-100S.  Back to cited text no. 1
Ranasinghe P, Perera YS, Senaratne JA, Abayadeera A. Preoperative testing in elective surgery: Is it really cost effective? Anesth Essays Res 2011;5:28-32.  Back to cited text no. 2
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Committee on Standards and Practice Parameters, Apfelbaum JL, Connis RT, Nickinovich DG, American Society of Anesthesiologists Task Force on Preanesthesia Evaluation, Pasternak LR, et al. Practice advisory for preanesthesia evaluation: An updated report by the American society of anesthesiologists task force on preanesthesia evaluation. Anesthesiology 2012;116:522-38.  Back to cited text no. 3
National Collaborating Centre for Acute Care (UK). Preoperative Tests: The use of Routine Preoperative Tests for Elective Surgery – Evidence, Methods and Guidance. London: National Institute of Clinical Excellence; 2003. Available from: http://www.ncbi.nlm.nih.gov/books/NBK48489/. [Last accessed on 2017 Mar 05].  Back to cited text no. 4
Karim HM. Practice and reasons for routine preoperative investigations among anaesthesiologists and surgeons: An online survey. Indian J Anaesth 2017;62:933-5.  Back to cited text no. 5
Benarroch-Gampel J, Sheffield KM, Duncan CB, Brown KM, Han Y, Townsend CM Jr., et al. Preoperative laboratory testing in patients undergoing elective, low-risk ambulatory surgery. Ann Surg 2012;256:518-28.  Back to cited text no. 6
Dzankic S, Pastor D, Gonzalez C, Leung JM. The prevalence and predictive value of abnormal preoperative laboratory tests in elderly surgical patients. Anesth Analg 2001;93:301-8.  Back to cited text no. 7
Reazaul Karim HM, Prakash A, Sahoo SK, Narayan A, Vijayan V. Abnormal routine pre-operative test results and their impact on anaesthetic management: An observational study. Indian J Anaesth 2018;62:23-8.  Back to cited text no. 8
Fayed A, Elkouny A, Zoughaibi N, Wahabi HA. Elective surgery cancelation on day of surgery: An endless dilemma. Saudi J Anaesth 2016;10:68-73.  Back to cited text no. 9
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Kaddoum R, Fadlallah R, Hitti E, El-Jardali F, El Eid G. Causes of cancellations on the day of surgery at a tertiary teaching hospital. BMC Health Serv Res 2016;16:259.  Back to cited text no. 10
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Demongeot J. Biological boundaries and biological age. Acta Biotheor 2009;57:397-418.  Back to cited text no. 13
Jetté M, Sidney K, Blümchen G. Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity. Clin Cardiol 1990;13:555-65.  Back to cited text no. 14
Wijeysundera DN, Sweitzer B. Preoperative evaluation. In: Miller RD, Eriksson LI, Fleisher LA, Wiener-Kronish JP, Cohen NH, Young WL, editors. Miller's Anesthesia. 8th ed. Philadelphia: Elsevier Saunders; 2015. p. 1091.  Back to cited text no. 15


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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