RU2846813C1 - Method for non-invasive screening of varicose disease of lower extremities at preclinical stage - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to therapy, phlebology, surgery, including vascular surgery. It can be used as non-invasive screening of varicose veins of lower extremities. At the preclinical stage, patient’s sex, age, smoking, feeling of heaviness in legs, varicose veins in close relatives are taken into account. Examination reveals the presence of convex nodular vascular lesions and skin rashes. In addition, operations for varicose veins in close relatives are taken into account, and based on the obtained data, a prognostic risk coefficient is calculated using the proposed mathematical formula. If the prognostic risk coefficient is higher than 0.607103919, then a high probability of the presence of varicose veins of the lower extremities is predicted and the patient must be directed to undergo an in-depth diagnosis and, if necessary, to plan a surgical method of treatment, and if the calculated coefficient is lower than or equal to 0.607103919, a low risk of varicose disease is predicted and, accordingly, such a patient does not need in-depth diagnostics.

EFFECT: method is simple, safe, improves detection of varicose veins.

1 cl, 1 dwg, 4 tbl, 3 ex

Description

The invention relates to medicine and can be used in therapy, surgery, vascular surgery, and phlebology. The method is presented as an original screening model for detecting varicose veins of the lower extremities, implemented as a questionnaire characterized by simplicity and accessibility for a wide range of respondents representing the adult population.

A known method for diagnosing venous pathology of the lower extremities involves the use of ultrasound equipment (Application 98104520/14 dated March 10, 1998; Application: 2020133294, dated October 9, 2020; Phlebology. A Handbook for Physicians edited by Academician V.S. Savelyev. Moscow: Medicine, 2001, pp. 71-91, 445-451), which involves performing Doppler ultrasound examination of the veins, assessing blood flow velocity, and diagnosing valve insufficiency. These methods are considered in-depth, hardware-based diagnostics of lower extremity vein problems and require specialized medical equipment and skills.

There is an invention called "A Method for Diagnosing the Nature of Lower Extremity Venous Lesions" (application no. 2002104509/14, dated February 19, 2002), which involves measuring the circumference of the affected and healthy limbs at different levels of the thigh and lower leg. Based on the obtained data, a quantitative indicator is calculated using a formula, and, depending on its value, embologenic or occlusive phlebothrombosis is diagnosed. This method is indicated for existing venous pathology and serves as a clarifying tool for already identified pathology; therefore, it also requires certain skills and abilities.

A method for predicting the recurrence of varicose veins in the lower extremities (application 2014126152/14 dated June 26, 2014) is developed. This method takes into account the patient's medical history, including a history of previous surgical treatment for varicose veins, as well as physical examination data. Specifically, it identifies poor posture, flat feet, pale skin, hyperextensibility of the skin, a positive wrist test, a positive thumb test, diastasis recti, myopia, and easily developing hematomas. The presence of five or more of these signs is used to predict recurrence of varicose veins in the lower extremities. This method requires specific skills in posture assessment and methods for detecting flat feet (plantography, X-ray) and therefore cannot be considered a screening diagnostic method.

Another method for identifying individuals at risk of developing decompensated forms of varicose veins of the lower extremities (application No. 2004107706/15 dated March 15, 2004) involves identifying the number of circulating endothelial cells in venous blood, and if their content is above 4*10 ⁴ cells per ml of blood, the onset of varicose veins is diagnosed; however, this method refers to a laboratory type of examination and is not a non-invasive screening.

The closest analogue chosen was the questionnaire "Phleboscore Test" - a method for assessing the potential risk of developing venous diseases. The test allows you to take preventive measures in time and avoid potential complications. Developed by Dr. Blanchemazon; Department of Vascular Medicine; Paris, France (Blanchemazon P. Practical assessment of venous risk: le Phleboscore®. Law Vase Int 2000;81:12-16.) It includes questions on risk factors (gender, age, sedentary lifestyle, overweight, number of pregnancies, working conditions, family history, sports), as well as questions on the frequency of symptoms (heavy legs, feeling of swelling) and circumstances in which symptoms worsen (heat, birth control pills, long trips). Scores range from 0 to 31. A score >12 identifies patients at risk for cardiovascular disease, while a score >23 indicates the need for a more detailed venous examination. However, this test only includes a score and relies on a comprehensive assessment without considering the significance and validity of individual criteria.

The aim of our proposed method is to increase the reliability of non-invasive screening of varicose veins of the lower extremities at the preclinical stage through the use of multivariate statistical modeling.

The rationale for the need for a new screening approach is based on compliance with the known Wilson-Jungner criteria:

1. Varicose veins are a common disease that is becoming an important public health problem;

2. The pathogenesis of varicose veins is well studied today;

3. The disease is characterized by slow progression and the presence of an early stage at which clinical manifestations of the disease are minimal;

4. Timely surgical treatment and, in general, therapy of varicose veins in the early stages allows us to effectively combat the problem of VBNK;

5. The screening program increases the detection of varicose veins, many cases of which remain undiagnosed due to low patient referral rates;

6. Analysis of the main operational characteristics of the proposed screening model demonstrated the acceptability of the original medical diagnostic technology in relation to disease detection, identification of patient groups for surgical treatment and the risk of disease recurrence;

7. The proposed screening method has the potential to cover large populations and increase the likelihood of identifying patients with varicose veins who might otherwise remain undiagnosed. Taking into account individual risk factors and the nature of the disease, optimal intervals between follow-up examinations can be determined, allowing for the efficient use of healthcare resources while maintaining the effectiveness of screening.

8. This screening model in the diagnostic cascade of patient examination for varicose veins is an effective tool for early detection and prevention of disease progression. Providing additional diagnostic and therapeutic interventions, as needed as a result of screening, improves patients' quality of life and reduces long-term healthcare costs.

9. The medical technology used is safe, as it cannot cause physical harm to patients. Patient education and psychological support measures, including those in the event of disease detection, should minimize psychological stress. Identifying risk factors, detecting early forms of the disease, predicting outcomes, and promptly treating and correcting risk factors can improve quality of life and prevent damage from complications of varicose veins.

10. A simple paper test during a visit to a specialist for any reason is the least expensive medical service compared to other medical diagnostic technologies.

An assessment of the quality and effectiveness of the proposed original screening model was carried out with the calculation of the main operational (working) characteristics of this diagnostic test:

□ Sensitivity (abbr. Se): the probability that a test result will be positive in the presence of a disease;

□ Specificity (abbr. Sp): the probability that a test result will be negative in the absence of a disease;

□ Positive predictive value (abbr. +PV): the probability that a disease is present when the test is positive;

□ Negative predictive value (abbreviated -PV): the probability that the disease is absent when the test is negative.

□ Positive likelihood ratio (abbreviated +LR): the ratio between the probability of a positive test result in the presence of a disease and the probability of a positive test result in the absence of the disease;

□ Negative likelihood ratio (abbreviated -LR): the ratio of the probability of a negative test result in the presence of a disease to the probability of a negative test result in the absence of the disease.

□ Youden's index (J) is the difference between the proportion of true positive results (test sensitivity) and the proportion of false positive results. The greater this difference, the better the performance of the diagnostic technology;

□ Diagnostic efficiency of a test or accuracy (Accuracy, abbreviated Ace): the overall probability that a patient will be correctly classified is defined as the proportion of all tests that give the correct result;

□ The predictive summary index (PSI) reflects the overall gain in disease confidence from performing a diagnostic test.

Given the high prevalence of the disease in the population and limited healthcare system resources, it is important at the screening stage to identify factors that contribute to an unfavorable course of the disease and potentially identify those forms and cases of the disease for which surgical treatment is essential. This should also take into account the factors that determine patient compliance with regard to radical intervention for VLB. When assessing the quality of the developed diagnostic test in this aspect, screening demonstrated the high significance of its main performance characteristics: sensitivity and specificity were 63.54% [CI=95%: 58.4-88.4] and 87.44% [CI=95%: 67.3-99.7], respectively.

The key operating characteristics (coefficients) of the logistic regression statistical model for predicting the probability of a medical intervention decision were calculated. The data are presented in Table 1.

Subsequently, in order to identify a possible combination of the selected variables, a regression equation was constructed, on the basis of which a single analytical scale of prognostic values with an optimal combination between sensitivity and specificity, determined by the subsequent ROC analysis procedure, was verified (see Fig. 1).

The stated goal is achieved by the fact that during the survey, possible risk factors are taken into account and, based on the data obtained, the prognostic risk coefficient (PRC) is calculated as the classification value of the regression equation according to the formula:

PP - sex of the patient undergoing screening: 101 - male, 102 - female,

VP - age of the patient undergoing screening: 101 - 18-44 years, 102 - 45-59 years, 103 - 60-74 years. 104 - 75 and older,

BMI - body mass index, kg/ ^m2 : 101 - less than 25, 102 - 25-29.99, 103-30 and more,

CO - the presence of large, convex, nodular vascular formations on the lower extremities: 101 - no, 102 - yes,

KB - presence of skin rashes: 101 - no, 102 - yes,

CHTN - feeling of heaviness in the legs: 101 - no, 102 - yes,

VBR - varicose veins in close relatives: 101 - no, 102 - yes,

OBR - operations for varicose veins in close relatives, 101 - no, 102 - yes,

KU - smoking: 101 - no, 102 - yes,

and if the RCC is higher than 0.607103919, then a high probability of the patient having varicose veins of the lower extremities is predicted and the patient must be referred for in-depth diagnostics, including the use of invasive screening methods and, if necessary, planning of a surgical treatment method, and if the RCC is lower than or equal to 0.607103919, then a low risk of varicose veins is predicted and, accordingly, such a patient does not need in-depth diagnostics.

The novelty of the proposed solution lies in the fact that for the first time, patients visiting an outpatient medical facility have the opportunity to undergo a screening questionnaire to identify the risk of varicose veins and, through the use of multivariate modeling, solve a logistic regression equation. This provides high efficiency and reliability in identifying varicose veins of the lower extremities in the population, ensures optimal patient routing within the diagnostic cascade, and also allows for the prediction of the likelihood of disease recurrence.

Technical solutions that have features that coincide with the distinctive features of the method we propose have not been identified, which allows us to conclude that the proposed method meets the criterion of “inventive step”.

The proposed method is clearly illustrated by the following examples.

Example 1

Woman B, 39, visited a surgeon at her local clinic complaining of leg pain. The surgeon suggested she complete a questionnaire using the developed method. The questionnaire responses were as follows (see Table 2).

Based on the obtained data, the prognostic risk coefficient (PRC) was calculated as the classification value of the regression equation using the formula:

The resulting value was 1.035613, which is higher than the cutoff point (association criterion) of 0.607103919, and predicts a high probability of varicose veins in the lower extremities. The patient was referred for an in-depth diagnostic procedure, specifically an ultrasound examination of the veins of the lower extremities, which confirmed the presence of varicose veins and identified indications for surgical intervention. The patient underwent surgery, and there have been no recurrences of the disease over the past two years.

Example 2.

Woman A, 42, visited a surgeon at her local clinic complaining of heaviness in her legs. The surgeon suggested she complete a questionnaire using the developed method. The questionnaire responses were as follows (see Table 3).

Based on the obtained data, the prognostic risk coefficient (PRC) was calculated as the classification value of the regression equation using the formula:

The obtained value was -1.848367, which is below the cutoff point (association criterion) of 0.607103919 and predicts a low probability of varicose veins in the lower extremities. The patient did not require further examination. Pain and heaviness no longer bothered her. No repeat visits regarding leg veins were recorded over the course of two years.

Example 3.

To evaluate the effectiveness of the proposed approach, a survey was conducted using a retrospective approach with a 43-year-old patient M. with a known anamnesis from the outpatient card and medical history after surgical treatment of ulcerative manifestations of varicose veins of the lower extremities, which were not diagnosed in time and such manifestations developed.

Patient M, 43, presented to a surgeon complaining of a rash on his legs. Upon examination, the surgeon did not suspect any vascular pathology and referred the patient to a dermatologist, who diagnosed him with dermatitis, which was treated locally. However, the rash progressed, and ulcers developed within 6 months. He returned to the vascular surgeon and was referred for an ultrasound of his lower extremities, which diagnosed varicose veins complicated by thrombophlebitis. The patient underwent surgery, and the residual ulcers healed within 1 year. After reviewing the patient's medical records and medical history, a questionnaire was completed at the time of the initial visit (see Table 4).

Based on the obtained data, the prognostic risk coefficient (PRC) was calculated as the classification value of the regression equation using the formula:

The obtained value was 2.386619, which is higher than the cutoff point (association criterion) of 0.607103919, and predicts a high probability of varicose veins in the lower extremities. However, the patient was not offered a proper in-depth examination, which led to the development of the disease and all the other negative consequences, all of which could have been avoided with timely diagnosis and early treatment.

The proposed method was applied at the Yaroslavl Phlebology Center Doctor Ven LLC.

Claims (12)

A method for non-invasive screening of varicose veins of the lower extremities at the preclinical stage, including taking into account the patient's gender (PG), patient's age (PA), determination of body mass index (BMI), feeling of heaviness in the legs (SHL), varicose veins in close relatives (VCR), characterized in that the presence of convex nodular vascular formations on the legs (NO) and skin rashes (SR) are detected by examination, operations for varicose veins in close relatives (OR), smoking (KU) are taken into account and, based on the data obtained, the prognostic risk coefficient (PRC) is calculated as the classification value of the regression equation according to the formula: RCR=338.40819 - PP×0.88242 - VP×0.068359 - BMI×0.036996 - CO×2.77180 + KV×0.39623 - CHTN×0.66185 - VBR×0.16140 + OBR×0.62743 + KU×0.23026, where PP - gender of the patient undergoing screening: 101 - male, 102 - female; VP - age of the patient undergoing screening: 101 - 18-44 years, 102 - 45-59 years, 103 - 60-74 years, 104 - 75 and older; BMI - body mass index, kg/ ^m2 : 101 - less than 25, 102 - 25-29.99, 103 - 30 and more; CO - the presence of convex nodular vascular formations on the lower extremities: 101 - no, 102 - yes; KB - presence of skin rashes: 101 - no, 102 - yes; CHTN - feeling of heaviness in the legs: 101 - no, 102 - yes; VBR - varicose veins in close relatives: 101 - no, 102 - yes; OBR - operations for varicose veins in close relatives: 101 - no, 102 - yes; KU - smoking: 101 - no, 102 - yes, and if the RCC is higher than 0.607103919, then a high probability of the patient having varicose veins of the lower extremities is predicted and the patient must be referred for in-depth diagnostics, including the use of invasive screening methods, and, if necessary, planning of a surgical treatment method, and if the RCC is lower than or equal to 0.607103919, then a low risk of having varicose veins is predicted and, accordingly, such a patient does not need in-depth diagnostics.