|Year : 2018 | Volume
| Issue : 2 | Page : 121-125
Prevalence and impact of abnormal routine pre-operative test results among elective surgical patients with or without co-morbidity: An observational comparative study
Narayanan Rajaram1, Habib Md Reazaul Karim2, Avinash Prakash1, Sarasa Kumar Sahoo1, Mridul Dhar1, Anilkumar Narayan1
1 Department of Anaesthesiology, Andaman and Nicobar Islands Institute of Medical Sciences and GB Pant Hospital, Port Blair, Andaman and Nicobar Islands, India
2 Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
|Date of Web Publication||19-Jul-2018|
Habib Md Reazaul Karim
Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Raipur, Chhattisgarh
Source of Support: None, Conflict of Interest: None
Background: At present, selective and clinical assessment-based pre-operative investigations are advocated, but it is yet far from routine practice. Aim: This study aims to assess the prevalence and impact of abnormal routine pre-operative test results among co-morbid and non-co-morbid elective surgical patients. Methods: Data for this prospective study were collected by reviewing the medical charts of the patients attending pre-anaesthetic clinic from December 2016 to April 2017. The cohort was divided into non-co-morbid and co-morbid. Routine pre-operative tests were done, their results and impacts of abnormal test results were noted; number needed to investigate (NNI) was calculated. Data were compared using Fisher's exact test, unpaired t-test, etc., P < 0.05 was considered statistically significant. Results: Data from 887 patients; 322 (36.30%) co-morbid were analysed. Co-morbid patients were older (53.79 ± 14.99 vs. 40.33 ± 15.68 year). No difference was found in the number of tests done in co-morbid patients except significantly higher number of electrocardiogram and echocardiography (P < 0.0001). Abnormal test results were significantly higher among co-morbid (relative risk – 1.63, P < 0.0001). Impacts were similar in co-morbid as compared to non-co-morbid for most of the tests, but thyroid function and blood sugar tests showed NNI for significant impact below 10 in co-morbid group. Conclusion: Co-morbid patients have more abnormal results than non-co-morbid patients, but impacts of such tests are nearly indifferent. Routine testing is not favourable even in co-morbid patients. Selective or co-morbid disease-specific tests are having more significant impacts and should replace the 'routine testing' even in co-morbid patients.
Keywords: Abnormality results, co-morbidity, laboratory tests, outcome, pre-operative, surgery
|How to cite this article:|
Rajaram N, Karim HM, Prakash A, Sahoo SK, Dhar M, Narayan A. Prevalence and impact of abnormal routine pre-operative test results among elective surgical patients with or without co-morbidity: An observational comparative study. Niger Postgrad Med J 2018;25:121-5
|How to cite this URL:|
Rajaram N, Karim HM, Prakash A, Sahoo SK, Dhar M, Narayan A. Prevalence and impact of abnormal routine pre-operative test results among elective surgical patients with or without co-morbidity: An observational comparative study. Niger Postgrad Med J [serial online] 2018 [cited 2022 Jul 1];25:121-5. Available from: https://www.npmj.org/text.asp?2018/25/2/121/237085
| Introduction|| |
The term 'routine test' was defined as a test ordered in the absence of a specific clinical indication or purpose. Designations such as 'pre-operative status' or 'surgical screening' used globally are not specific clinical indications for pre-operative investigations. Pre-operative tests are done to know the progress of a known disease. Although not acceptable or without controversy, it is also done to detect hidden co-morbid conditions. However, the value of such testing is seriously questioned. At present, selective and clinical assessment-based pre-operative investigations are advocated., History and clinical assessment are done to know/suspect a co-morbid condition which can guide us in deciding selective investigations. Several studies have assessed the value of pre-operative investigations in the American Society of Anesthesiologists (ASA) physical status I and II or among ambulatory or minor surgical patients.,,, However, the study specifically focusing 'routine test' in co-morbid patients undergoing any category non-cardiac surgery is scarce or nil. The present study was aimed to assess the impacts of abnormal routine pre-operative test results among co-morbid patients and compare it with non-co-morbid patients.
| Methods|| |
The present prospective, single centre, observational study was conducted in Andaman and Nicobar Islands Institute of Medical Sciences, a tertiary care public sector teaching hospital of Port Blair, India (CTRI/2018/01/011235). The associated hospital serves predominantly as a secondary level and also a tertiary level healthcare provider with limited super specialist surgical patients. Institutional research review board and ethical approval (Ethics Committee, Andaman and Nicobar Islands Institute of Medical Sciences, Port Blair, India. Reg No. ECR/940/Inst/AN/2017) was obtained (Letter Ref No. ANIIMS/IEC/2017-2 dated 18/07/2017) and patients were informed about recording of data and its future use. The patients attending pre-anaesthetic evaluation clinic (PAEC) from December 2016 to April 2017 for planned elective non-cardiac surgery were included. Patients of aged 12 years or more, of both the sexes belonging to any ASA physical class undergoing any National Institute for Health and Care Excellence (NICE) class of surgery were included. A total of 11 qualified anaesthesiologists were there and were involved in pre-operative evaluation and risk assessment and all of them were aware about ongoing data collection. No intervention was done by the data collector as well as primary investigator to change the process of ongoing assessment and evaluation, and data for this study were collected from the completed PAEC record sheet, reviewing the medical chart and investigations already done. The cohort was divided based on the presence of medical co-morbidity (i.e., non-co-morbid and co-morbid group). Occasional alcohol drinker and smoker were not regarded as co-morbid; however, alcohol dependence or abuse was taken as a co-morbid condition. All the patients who were known cases of medical co-morbidities such as hypertension, diabetes and hypo/hyperthyroidism were categorised in the co-morbid group.
Demographic, physical status, surgical category, clinical/medical history, pre-operative tests done and their results in terms of normal and abnormal were noted. Haemoglobin level of <12 g% was noted as anaemic in this study. Platelet count of <100,000/mm 3, prothrombin time increased by >4 s than control and/or INR of >1.5 was regarded abnormal. Blood sugar level of >250 mg% was taken as uncontrolled as well as significant abnormality to change perioperative anaesthetic management. Other test results were determined as normal/abnormal as per the reference value provided by the laboratory. Electrocardiogram (ECG) and chest X-ray were regarded abnormal if the evaluating anaesthesiologist or physician noted anything other than sinus rhythm or within normal limit, respectively. An abnormal test result was considered as impactful if only the evaluating anaesthesiologist asked for a consultation/referral, retesting or further investigating the patient's condition based on the abnormal report. However, an impact was considered as significant only if the impact (i.e., referral, retesting, etc.,) outcome or abnormal test, lead to a change in perioperative anaesthetic management (i.e., postponing the elective case, intra-operative intensive monitoring or gross deviation from the standard anaesthetic management). Echocardiography done in known cardiac patients and those were asked after initial assessment was not considered as routine and were excluded from analysis.
The study was designed with a hypothetical abnormal test results in non-co-morbid and co-morbid as 10% and 20%, respectively, along 1-α of 95% and a power of 80%. As the incidence of non-co-morbid and co-morbid are different and the sampling was non-randomised in nature, a ratio of unexposed (non-co-morbid) to exposed (co-morbid) 1.5 and design effect of 1.8 was taken. This gave a sample for non-co-morbid cohort as 427 and co-morbid as 285 using online statistical tool OpenEpi (Open Source Epidemiologic Statistics for Public Health; http://www.openepi.com). A minimum of 500 participants in non-co-morbid and 300 in co-morbid group was targeted during data collection.
Data were presented in absolute number and percentage scale. The impacts of abnormal test results were also calculated in absolute number and percentage scale. The number needed to investigate (NNI) for impacts as well as significant impact were also calculated. Measures of central tendencies and dispersions were calculated and comparison of the groups was done by Fisher's exact test and unpaired t-test using INSTAT software (GraphPad Prism Software, La Jolla, CA, USA). P < 0.05 was considered statistically significant.
| Results|| |
A total of 887 files of patients aged between 12 and 95 years; median age 44 year, who completed the PAEC procedure for elective surgeries during the study period were included for analysis. Four hundred and twenty-three (47.69%) of the patients were male and median ASA physical status was II of the entire cohort. Three hundred and twenty-two (36.30%) patients were having at least one medical co-morbid condition and were compared with 565 (65.70%) non-co-morbid patients. Co-morbid patients were older as compared to non-co-morbid patients (median [age range] 38 [12–85] vs. 56.5 [14–95] year; P < 0.0001). The age, sex, ASA physical status classes and NICE surgical grade-wise distributions and comparison are shown in [Table 1].
|Table 1: Demographic, physical and surgical grades compared using unpaired t-test. data expressed in mean±standard deviation (95% confidence interval) or n (%) or median/interquartile range (q3 - q1)|
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A total of 6076 tests (3781 in non-co-morbid and 2295 in co-morbid) were evaluated. Average number of routine tests per patient was slightly higher in co-morbid group (7.13 vs. 6.69). A significantly higher number of ECG and echocardiography (P< 0.0001) were done routinely in patients having co-morbidity as compared to those without having co-morbid conditions. The distribution of routine tests done and their comparison is presented in [Table 2].
|Table 2: Total tests done in non-co-morbid and co-morbid patients and their comparison using Fisher's exact test|
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A total of 402 (17.52%) abnormal test results were found in co-morbid group as compared to 406 (10.74%) in non-co-morbid group and the difference was statistically significant (relative risk: 1.63, 95% confidence interval 1.43–1.85; P < 0.0001). Except for blood counts, coagulation profile and liver function test; all other routine tests had significantly more abnormal results among co-morbid group [Table 3].
|Table 3: Abnormal test results in non-co-morbid and co-morbid patients and their comparison using Fisher's exact test|
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Although co-morbid group had significantly more abnormal blood sugar levels (16.72% versus 3.98%); the impacts were significantly lesser as compared to non-co-morbid group for these abnormal results (20.75% vs. 54.55%). The most common impact of non-co-morbid patients was repeat testing and referral. The impacts of the other abnormal routine test results were similar for both the groups (P > 0.05 for all) [Table 4]. The numbers of significant impacts by the abnormal test results were also not statistically different among the groups [Table 5]. While the NNI for having an impact was >10 for serum electrolytes, blood sugar levels, ECG, thyroid function test (TFT) for both co-morbid and non-co-morbid, only blood sugar levels and TFT had the NNI for significant impacts <10. The NNI for impacts and significant impacts of abnormal test results are shown in [Table 6].
|Table 4: Impacts of abnormal test results in non-co-morbid and co-morbid patients and their comparison using Fisher's exact test|
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|Table 5: Significant impacts of abnormal test results in non-co-morbid and co-morbid patients and their comparison using Fisher's exact test|
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|Table 6: Number needed to investigate for an impact and significant impacts in non-co-morbid and co-morbid patients and their comparison using Fisher's exact test|
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| Discussion|| |
The findings of the present study indicate that the routinely practiced pre-operative tests were able to pick up more abnormalities in co-morbid patients as compared to non-co-morbid (P< 0.05). However, it was also found that these abnormalities were not having more impacts in terms of consultation/referrals or further testing, etc., than non-co-morbid patients. The ASA statement indicates that pre-operative tests may be indicated for discovery or identification of a disease or disorder which may affect perioperative anaesthetic care. It is also indicated for verification or assessment of an already known disease, disorder, medical or alternative therapy which may affect perioperative anaesthetic care. It also stated that routine laboratory or diagnostic screening test is not necessary; rather, specific clinical indicators or risk factors should be identified for the appropriate ordering of tests. Pre-existing disease or medical co-morbidity is listed as one of such indications. Although the thought and practice of pre-operative risk assessment has evolved steadily toward a more systematic approach and the past practices of battery testing to elicit any and all possible data has changed to the concept of clinically indicated tests over the last three decades, the practice of routine testing is still rampant.,
A Brazilian study found that pre-operative tests were ordered more in patients with increasing morbidity. The present study also showed that the average number of pre-operative routine tests were slightly higher in co-morbid patients (7.13 vs. 6.69 tests per head). Now the question arises whether the practice of routine testing is correct in co-morbid patients? Or, do all the tests done in co-morbid group are valuable in findings the hidden abnormalities? If yes; is it having a significant impact in changing perioperative anaesthetic management and healthcare cost? Interestingly, it was found that the abnormal blood sugar levels, despite being smaller in number in non-co-morbid group had more impacts in terms of referral/consultation. This was probably because these results were unexpected and will mostly require follow-up as well treatment for diabetes although their blood sugar levels were not very high enough to change anaesthetic management by causing postponement of elective surgery on scheduled day. Therefore, significant impacts were not so different among co-morbid and non-co-morbid groups. There is general consensus that an attempt should be made to control the upper limit of glucose to <200 mg/dL. However, a blood sugar level >400 mg% only demands postponement of elective surgery., A blood sugar level of 250–400 mg% requires an intensive blood sugar management night or the day before surgery and take up the case as elective on the scheduled day itself. A blood sugar level of 180–250 mg% can be taken up with on-going management with insulin with intra-operative intermittent monitoring of blood sugar in case of prolonged major surgeries; and for this, we have to know the blood sugar level and have to do the test. However, this does not mean that each and every patient needs blood sugar testing. Rather, the specific patient should be identified in PEAC or outpatient department from the history and clinical examinations. Although effective, pre-operative testing should not be used as screening testing for detecting a hidden disease.
It has been shown that pre-operative investigations relying on full medical history and physical examination are more specific, can eliminate unnecessary tests and could notably increase efficiency without affecting the quality of care. The present finding (i.e., having more and significant numbers of impacts in the co-morbid group) indirectly supports these findings. Still, routine testing cannot be advocated in these co-morbid (or ASA– II, III, IV etc) patients. It is because, although the number of unnecessary tests become lesser with increasing ASA physical status classes from I to III; ASA-IV patients are actually underinvestigated/underevaluated with routine format of testing.
The present study has found that specific abnormal tests results such as blood sugar and thyroid functions in co-morbid category had significantly higher abnormal test results [Table 3]. This indicates that, not assessing for those is likely to lead to cancellation or postponement as shown by previous studies., As hypothyroidism and diabetes constituted a major bulk of the co-morbid patients in this study, this finding indicates that testing done based on history and co-morbidity is unlikely to miss such abnormalities even if we abandon routine practice. Moreover, the data (tables) indicate and reiterate that mere presence of an abnormal test result in routine testing does not change anaesthetic or perioperative management in most of the patients. Hence, if we answer the question 'whether the practice of routine testing is correct in co-morbid group?', the answer from the present study findings and discussion indicates towards 'no'. However, the present study findings do indicate that co-morbid patients are having more abnormal test results which even lead to increased number of significant impacts and should be investigated specifically according to their co-morbidity.
| Conclusion|| |
Co-morbid patients have more abnormal results than non-co-morbid patients but impacts of such tests are nearly indifferent. Routine testing is not favourable even in co-morbid patients. However, selective or co-morbid disease-specific tests are having more significant impacts and should replace the 'routine testing' even in co-morbid patients.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]