Efforts towards standardization and globalization of heath care are occurring in different aspects of medicine and health policy [
U codes (U00–U99), also called codes for special purposes, are in Chapter XXII of the fourth edition of ICD-10 [
One approach towards better health care is quantification of the burden of disease [
Using DALYs, the burden of different diseases and risk factors have been analyzed in Korea using nationally representative data provided by health-related government agencies such as the Health Insurance Review & Assessment Service (HIRA) and National Health Insurance Service (NHIS) [
Because data with main disease codes not covered by KCD 6 were overlooked in previous studies of the burden of disease, this study hypothesized that the collection of the subdisease codes within a year of data collection would reflect what was covered by the main disease code. In other words, the assumption was that, within the annual collection of data, the combination of main disease code and subdisease code would cover the diseases for a patient throughout a year.
U codes can be divided into three components (Table
Summary of U codes or code for special purposes in the Korean Classification of Diseases 6, which was revised in 2009.
3-digit code | Code name | Number of 4-digit subcategories |
---|---|---|
|
|
|
U20-U21 | General diseases | 12 |
U22 | Mental and behavioral disorders | 3 |
U23-U24 | Diseases of the nervous system | 12 |
U25 | Diseases of eye, tongue, and throat | 6 |
U26 | Diseases of the circulatory system | 4 |
U27 | Diseases of the respiratory system | 8 |
U28 | Diseases of the digestive system | 10 |
U29 | Diseases of the skin and subcutaneous tissue | 8 |
U30 | Diseases of the musculoskeletal system and connective tissue | 7 |
U31 | Diseases of the genitourinary system | 10 |
U32 | Diseases of the female genitourinary system and those related to pregnancy | 8 |
U33 | Diseases of retardation and development, childhood, and adolescence | 9 |
|
||
|
|
|
U50 | Disease pattern/syndrome of six excesses | 9 |
U51–U57 | Disease pattern/syndrome of the six meridians | 45 |
Greater yang disease pattern/syndrome | 14 | |
Yang brightness disease pattern/syndrome | 6 | |
Lesser yang disease pattern/syndrome | 6 | |
Greater yin disease pattern/syndrome | 3 | |
Lesser yin disease pattern/syndrome | 10 | |
Reverting yin disease pattern/syndrome | 6 | |
U58 | Disease pattern/syndrome of defense-qi-nutrient-blood | 9 |
U59 | Disease pattern/syndrome of triple energizer | 4 |
U60–63 | Disease pattern/syndrome of qi-blood-yin-yang-fluid-humor | 30 |
Disease pattern/syndrome of qi | 6 | |
Disease pattern/syndrome of blood | 6 | |
Disease pattern/syndrome of qi-blood-yin-yang | 9 | |
Disease pattern/syndrome of fluid and humor | 9 | |
U64–U79 | Disease pattern/syndrome of viscera and bowels | 94 |
Liver disease pattern/syndrome | 14 | |
Heart disease pattern/syndrome | 12 | |
Spleen disease pattern/syndrome | 7 | |
Lung disease pattern/syndrome | 11 | |
Kidney disease pattern/syndrome | 8 | |
Gallbladder disease pattern/syndrome | 4 | |
Stomach disease pattern/syndrome | 5 | |
Large intestine disease pattern/syndrome | 4 | |
Small intestine disease pattern/syndrome | 3 | |
Bladder disease pattern/syndrome | 2 | |
Disease pattern/syndrome of thoroughfare, conception vessels, and uterus | 7 | |
Combined disease pattern/syndrome of viscera and bowels | 17 | |
|
||
|
|
|
U95 | Soeumin disease pattern/syndrome | 5 |
U96 | Soyangin disease pattern/syndrome | 5 |
U97 | Taeumin disease pattern/syndrome | 5 |
U98 | Taeyangin disease pattern/syndrome | 3 |
The National Health Insurance Service-National Sample Cohort (NHIS-NSC) of 2012, which includes data for 1 million patients, was used for data analysis. NHIS-NSC data provide information on the utilization of healthcare based on the NHI claims from medical institutions to the NHIS from inpatient and outpatient clinic visits for each individual patient [
The primary goal was to use the data from the U code visits that also had subdisease codes in 2012 to the remaining visits with only U codes as main disease codes and without any subdisease codes.
The method to redistribute the U codes to KCD 6 codes was derived from garbage codes [
First, U codes as the main disease code were collected, which accounted for 151,967 visits in 2012. These data became the target for data analysis, which was conducted with the 30 most commonly used U codes, covering approximately 80% of the total U code visits. Then, the subdisease codes and their frequencies were collected. In this process, subdiseases coded with U codes, S codes (injury, poisoning, and certain other consequences of external causes), R codes (symptoms, signs, and abnormal clinical and laboratory findings, NEC), and Z codes (factors influencing health status and contact with health services) were excluded before determining the frequencies.
Before the redistribution of the main disease U codes to subdisease KCD 6 codes, a reorganizing process was conducted to rule out the codes that were irrelevant to the main disease codes. Subdisease codes can be used for diseases other than the main disease in many cases. To avoid this problem, only subdisease codes that were relevant to the main U codes were selected by doctors of Korean medicine, and the final decision was based on agreement of trained KMD doctors. For example, in the case of U303 (neck stiffness), the codes that were not directly related to pain or abnormal sensation of the neck, such as digestive disorders or urinary disorders, were removed. This process was based on consultation with medical professionals and professors and researchers at the College of Korean Medicine, Kyung Hee University, as well as review of the beta version of ICD-11, which includes traditional medicine in its structure based on the ICTM. By reviewing the beta version of ICD-11, the definition and explanation for each of the disorders or patterns in the U code were studied for the specific symptoms or signs replaced by KCD 6 codes. Symptoms or signs of the disorders or patterns in the U code that were not mentioned in the corresponding ICD-11 definition were removed before data analysis.
After selecting the KCD 6 codes among the subdisease codes and calculating the frequencies, each of the frequencies was replaced with the ratio of each U code and KCD 6 code within the total frequency of the corresponding U code. For example, in the case of U303 (neck stiffness), the frequency of the KCD 6 code in the subdisease code was converted into an intercode proportion, which equaled 1, within U303:
However, when the frequency of the corresponding KCD 6 codes did not exceed 1,500, which was about 1% of the total U code frequency in our data, this process could result in overfitting of the total data. The process was designed under the assumption that the diseases in the KCD 6 codes followed a normal distribution; however, when the morbidity of the disease is too low, this process could stretch the proportion over the actual morbidity. Therefore, in such cases, the actual frequency, instead of the expected frequency, within the total U code data was used to calculate the proportion
Furthermore, the cooccurrence of U codes and the corresponding KCD codes was visualized to show the relationship between the burdens of disease based on U codes and KCD 6 codes. Specifically, each of the inter-U code proportions was visualized to show the relationship between the U codes and KCD 6 codes in the NHIS-NSC data from 2012.
The data were analyzed using SAS 9.3 (SAS Institute), and the data were visualized using Python.
Table
Thirty most commonly used U codes in Korea, 2012.
Code | Name | Frequency (2012) |
---|---|---|
U303 | Neck stiffness | 6,552 |
U240 | Numbness | 3,142 |
U234 | Sequela of wind stroke | 2,680 |
U670 | Pattern/syndrome of heart fire flaming upward | 1,684 |
U238 | Impediment disease |
1,323 |
U280 | Food accumulation | 768 |
U680 | Pattern/syndrome of spleen qi deficiency | 717 |
U301 | Painful impediment | 551 |
U305 | Crane-knee arthritis | 488 |
U304 | Joint-running wind | 480 |
U241 | Insensitivity | 462 |
U651 | Pattern/syndrome of liver qi depression | 458 |
U306 | Muscle cramp | 411 |
U236 | Tremor | 392 |
U222 | Fire disease, hwa-byung | 362 |
U221 | Depression, melancholy, and depressive syndrome | 326 |
U302 | Fixed impediment | 325 |
U650 | Pattern/syndrome of ascendant hyperactivity of liver yang | 306 |
U730 | Pattern/syndrome of stomach qi deficiency | 291 |
U230 | Head wind | 270 |
U710 | Pattern/syndrome of kidney qi deficiency | 264 |
U660 | Pattern/syndrome of heart qi deficiency | 246 |
U640 | Pattern/syndrome of liver blood deficiency | 233 |
U233 | Prodrome of wind stroke | 231 |
U794 | Pattern/syndrome of spleen and kidney yang deficiency | 225 |
U784 | Pattern/syndrome of liver and kidney yin deficiency | 222 |
U332 | Night crying | 199 |
U260 | Chest impediment | 197 |
U600 | Qi deficiency pattern/syndrome | 186 |
U204 | Consumptive disease | 173 |
The most commonly reported U code was U303, or neck stiffness. The most commonly used KCD 6 code in this analysis was related to musculoskeletal diseases (M codes), followed by diseases of the nervous system (G codes). Diseases of the digestive system (K codes) and mental and behavioral disorders (F codes) were also common. For example, U303 (neck stiffness) was redistributed to the following KCD codes: M791 (myalgia), M626 (muscle strain), M759 (shoulder lesion, unspecified), M758 (other shoulder lesions), M750 (adhesive capsulitis of shoulder or frozen shoulder), M255 (pain in joint), M542 (cervicalgia), M548 (other dorsalgia), M751 (rotator cuff or supraspinatus tear of rupture [complete, incomplete] not specified as traumatic), M796 (pain in limb), M549 (backache NOS), M531 (cervicobrachial syndrome), M501 (cervical disc disorder with radiculopathy), M797 (fibromyalgia), M624 (contracture of muscle), G568 (interdigital neuroma of upper limb), and G439 (migraine, unspecified).
Because KCD 6 codes corresponding to U codes were reviewed using the beta version of ICD-11 and with medical professionals prior to the redistribution process, there were no KCD codes without any relevance to the corresponding U codes. The proportions of the U codes to the KCD codes were fairly evenly distributed following the redistribution to enable comparison of the data from the 24,164 visits to the remaining 151,967 visits with only U codes as the main disease codes and without any subdisease codes and the additional adjustments to prevent overfitting values in the redistribution table. The U code proportions ranged from <1% to approximately 20% of the burden of disease for each KCD 6 code; there were few high proportions for each of the U codes (Table
Redistribution of U codes to Korean Classification of Diseases (KCD) 6 codes.
U code | U code proportion to each KCD 6 code | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
U303 | M791 | M626 | M759 | M758 | M750 | M255 | M542 | G442 | M548 | M751 | M796 | G568 | M549 | G439 | M531 |
9.25% | 9.56% | 9.02% | 17.62% | 5.62% | 4.73% | 2.79% | 16.91% | 11.08% | 14.29% | 2.96% | 21.85% | 7.75% | 10.13% | 9.37% | |
M501 | M797 | M624 | |||||||||||||
20.54% | 7.90% | 9.89% | |||||||||||||
|
|||||||||||||||
U240 | M179 | M626 | M759 | M758 | M541 | M538 | M175 | M171 | F453 | ||||||
11.58% | 8.49% | 5.17% | 6.85% | 77.35% | 7.55% | 20.38% | 2.70% | 10.58% | |||||||
|
|||||||||||||||
U234 | M545 | G518 | G510 | M179 | M796 | K30 | M791 | M544 | K580 | M255 | M171 | M759 | G819 | M542 | M752 |
1.39% | 33.08% | 6.12% | 2.19% | 3.47% | 2.32% | 1.09% | 1.44% | 35.92% | 2.36% | 4.34% | 1.81% | 7.82% | 0.67% | 7.98% | |
I693 | K590 | G430 | M626 | M139 | G810 | I691 | M199 | M509 | |||||||
4.31% | 8.95% | 11.94% | 1.39% | 6.41% | 14.68% | 6.99% | 2.94% | 4.22% | |||||||
|
|||||||||||||||
U670 | G470 | G519 | G64 | G442 | G439 | K088 | H819 | F454 | G909 | G438 | |||||
44.07% | 25.68% | 6.55% | 14.16% | 15.26% | 43.28% | 2.67% | 1.33% | 4.41% | 9.11% | ||||||
|
|||||||||||||||
U238 | M545 | M179 | M791 | M255 | M796 | M626 | M750 | K30 | G470 | M759 | G510 | G560 | M543 | M199 | H911 |
0.69% | 1.49% | 0.79% | 1.51% | 1.24% | 0.72% | 1.24% | 0.64% | 5.18% | 0.53% | 1.08% | 10.20% | 0.86% | 3.79% | 14.29% | |
M653 | M544 | M542 | M549 | G562 | M170 | M171 | F329 | M501 | M708 | ||||||
1.33% | 0.14% | 0.17% | 0.92% | 20.69% | 0.73% | 0.40% | 7.50% | 2.30% | 0.44% | ||||||
|
|||||||||||||||
U280 | K30 | G442 | K318 | G438 | G430 | G439 | F982 | K590 | |||||||
5.06% | 6.78% | 9.77% | 11.10% | 8.41% | 2.57% | 1.80% | 3.91% | ||||||||
|
|||||||||||||||
U680 | K30 | J310 | L80 | L208 | G442 | G700 | G470 | M542 | G439 | H521 | K522 | N944 | N959 | G245 | J300 |
1.89% | 6.53% | 5.40% | 11.96% | 2.77% | 17.54% | 2.71% | 0.25% | 1.53% | 1.49% | 5.43% | 1.67% | 2.69% | 1.36% | 1.59% | |
K121 | N946 | ||||||||||||||
0.64% | 3.72% | ||||||||||||||
|
|||||||||||||||
U301 | M545 | M759 | M544 | M511 | M791 | M543 | M626 | M171 | M255 | M549 | M238 | M624 | M758 | M796 | M179 |
0.28% | 0.99% | 0.50% | 2.70% | 0.16% | 0.68% | 0.20% | 0.56% | 0.30% | 1.09% | 2.41% | 2.45% | 0.44% | 0.22% | 0.09% | |
M750 | M771 | M109 | M139 | M753 | M797 | M170 | M700 | ||||||||
0.16% | 0.43% | 2.50% | 1.23% | 2.24% | 0.73% | 0.24% | 1.67% | ||||||||
|
|||||||||||||||
U305 | M796 | M179 | M791 | M159 | M255 | M626 | M722 | M729 | |||||||
2.17% | 1.09% | 0.49% | 1.46% | 0.83% | 0.26% | 3.94% | 0.71% | ||||||||
|
|||||||||||||||
U304 | G560 | M545 | M758 | M544 | M171 | M179 | M255 | M759 | M750 | M542 | M104 | M626 | M791 | M199 | |
36.40% | 0.15% | 1.86% | 0.35% | 1.16% | 0.29% | 0.36% | 0.30% | 0.38% | 0.18% | 6.82% | 0.09% | 0.05% | 0.97% | ||
|
|||||||||||||||
U241 | M626 | G20 | I693 | M179 | F453 | M759 | M531 | M758 | M480 | M511 | |||||
1.66% | 2.06% | 4.35% | 0.42% | 4.99% | 0.49% | 2.69% | 0.66% | 1.00% | 0.51% | ||||||
|
|||||||||||||||
U651 | M626 | M791 | G430 | M759 | M545 | M544 | M758 | F453 | G440 | M751 | G442 | M255 | F454 | F411 | F410 |
1.06% | 0.36% | 15.46% | 0.45% | 0.06% | 0.19% | 0.72% | 2.91% | 3.35% | 1.30% | 1.11% | 0.22% | 0.50% | 3.44% | 4.92% | |
G438 | M624 | M750 | |||||||||||||
1.05% | 1.01% | 0.11% | |||||||||||||
|
|||||||||||||||
U306 | M545 | M791 | K30 | M796 | M255 | M626 | M239 | M759 | M179 | M543 | M771 | G560 | F480 | M542 | M170 |
0.02% | 0.04% | 0.06% | 0.07% | 0.05% | 0.02% | 1.10% | 0.02% | 0.01% | 0.03% | 0.05% | 0.22% | 0.55% | 0.01% | 0.02% | |
|
|||||||||||||||
U236 | M179 | G258 | M159 | M626 | F459 | G250 | |||||||||
2.26% | 10.78% | 2.68% | 0.32% | 0.68% | 0.54% | ||||||||||
|
|||||||||||||||
U222 | M545 | M791 | K30 | G470 | M759 | M626 | M255 | F454 | H571 | F510 | M199 | M519 | M542 | M722 | M796 |
0.15% | 0.39% | 0.47% | 3.89% | 0.35% | 0.15% | 0.20% | 0.75% | 5.14% | 4.85% | 1.30% | 0.96% | 0.10% | 1.21% | 0.13% | |
K219 | M179 | F453 | G438 | G442 | I119 | ||||||||||
2.08% | 0.04% | 0.31% | 0.40% | 0.16% | 3.66% | ||||||||||
|
|||||||||||||||
U221 | G470 | F453 | F519 | G438 | F454 | ||||||||||
16.34% | 15.55% | 6.88% | 4.73% | 0.41% | |||||||||||
|
|||||||||||||||
U302 | M179 | M545 | M791 | M480 | M624 | M796 | M626 | M792 | M544 | M17 | M508 | M541 | G430 | G64 | M139 |
0.69% | 0.13% | 0.17% | 2.77% | 4.38% | 0.41% | 0.20% | 3.76% | 0.05% | 4.09% | 1.21% | 1.67% | 0.88% | 0.32% | 0.65% | |
M235 | M542 | ||||||||||||||
0.51% | 0.03% | ||||||||||||||
|
|||||||||||||||
U650 | M545 | M791 | M626 | M171 | M544 | G438 | G439 | G519 | F502 | M542 | M796 | M255 | M549 | ||
0.21% | 0.35% | 0.35% | 0.97% | 0.14% | 1.49% | 0.60% | 0.61% | 8.57% | 0.06% | 0.08% | 0.05% | 0.21% | |||
|
|||||||||||||||
U730 | K30 | C259 | K295 | K296 | C169 | ||||||||||
1.46% | 19.57% | 6.81% | 3.75% | 1.23% | |||||||||||
|
|||||||||||||||
U230 | T676 | G244 | G442 | ||||||||||||
11.43% | 0.56% | 5.82% | |||||||||||||
|
|||||||||||||||
U710 | M478 | M545 | F453 | M791 | M626 | G438 | M179 | M255 | N951 | ||||||
5.22% | 0.13% | 3.95% | 0.14% | 0.17% | 1.98% | 0.07% | 0.11% | 2.29% | |||||||
|
|||||||||||||||
U660 | G700 | ||||||||||||||
8.77% | |||||||||||||||
|
|||||||||||||||
U640 | M253 | M758 | M759 | M249 | |||||||||||
1.14% | 2.32% | 0.89% | 0.29% | ||||||||||||
|
|||||||||||||||
U233 | M622 | M179 | G442 | I630 | M796 | G501 | G819 | G909 | |||||||
2.26% | 0.57% | 1.89% | 15.00% | 0.45% | 0.42% | 0.76% | 0.55% | ||||||||
|
|||||||||||||||
U794 | K30 | M171 | M791 | M626 | N318 | M544 | M179 | F458 | F480 | M750 | M758 | M796 | N944 | ||
0.76% | 1.72% | 0.26% | 0.36% | 17.14% | 0.04% | 0.04% | 1.40% | 0.33% | 0.02% | 0.04% | 0.02% | 0.56% | |||
|
|||||||||||||||
U784 | M543 | M626 | M545 | L031 | M242 | M791 | H111 | M199 | M489 | M549 | E282 | M759 | |||
1.70% | 0.36% | 0.06% | 2.15% | 3.38% | 0.09% | 2.64% | 1.30% | 3.64% | 0.48% | 3.39% | 0.04% | ||||
|
|||||||||||||||
U332 | K30 | F982 | L211 | ||||||||||||
2.10% | 1.20% | 6.67% | |||||||||||||
|
|||||||||||||||
U260 | K219 | M626 | M624 | ||||||||||||
13.19% | 0.58% | 3.33% | |||||||||||||
|
|||||||||||||||
U600 | F500 | K30 | K590 | ||||||||||||
5.17% | 0.72% | 6.42% | |||||||||||||
|
|||||||||||||||
U204 | M545 | M750 | M759 | M796 | M170 | M544 | M626 | M255 | M772 | ||||||
0.09% | 0.67% | 0.36% | 0.42% | 0.85% | 0.09% | 0.08% | 0.09% | 0.94% |
Values are reported as the proportion of the U code in each KCD 6 code, %.
Figure
Visualization of the probability of the cooccurrence of the 30 most commonly used U codes in the 2012 National Health Insurance Service data in Korea and each chapter of the Korean Classification of Diseases 6 codes.
To our knowledge, this is the first study to incorporate U codes into the calculation of the burden of disease in Korea, with a specific focus on the analytic methods and results to assess the burden of diseases coded under U codes that have been overlooked in previous studies. Many of the U codes were redistributed within KCD 6 classifications for musculoskeletal diseases and diseases of the nervous system.
Until now, standardized compilations of methods for the analysis of traditional medicine in studies of the burden of disease have been lacking. Of the few studies that have focused on systematically understanding disease patterns explained in traditional medicine, some have shown possible links between the disorders and patterns and KCD or ICD [
Trend in health care utilization from the
2010 | 2011 | 2012 | |
---|---|---|---|
Number of patients | |||
WM | 44,818,780 (77.9%) | 45,200,513 (78.0%) | 45,764,919 (78.1%) |
KM | 12,689,192 (22.1%) | 12,724,688 (22.0%) | 12,795,918 (21.9%) |
Total treatment cost ($) | |||
WM | 31,211,729,553 (94.8%) | 33,173,091,418 (94.7%) | 34,616,590,233 (94.6%) |
KM | 1,701,831,541 (5.2%) | 1,838,759,399 (5.3%) | 1,962,494,521 (5.4%) |
Number of total claims | |||
WM | 604,017,783 (79.0%) | 615,979,142 (79.3%) | 682,586,833 (80.3%) |
KM | 91,356,214 (12.0%) | 92,010,198 (11.8%) | 96,378,959 (11.3%) |
Number of outpatient claims | |||
WM | 593,702,030 (78.8%) | 605,084,745 (79.0%) | 670,812,474 (80.0%) |
KM | 91,227,649 (12.1%) | 91,850,417 (12.0%) | 96,181,670 (11.5%) |
WM: Western medicine; KM: Korean medicine.
The redistribution of many of the U codes into musculoskeletal diseases and diseases of the nervous system based on the KCD 6 supports the results of previous studies, in which Korean medicine was mainly utilized for musculoskeletal diseases [
Although the data were limited to claims records from the NHIS-NSC, the results of the present study show how each of the disorders or patterns in Korean medicine can be understood in terms of KCD 6 codes. This data-driven approach provides a new perspective in understanding and explaining disorders and patterns in Korean medicine, or within the larger scope of traditional medicine, via the disease classification system in Western medicine [
There are a few limitations in our study. First, the data source was based on claims from medical institutions to the NHIS. In other words, the data source and analysis did not include health care services not covered by the NHIS, including the out-of-pocket (OOP) sector. It is important to note that the portion of Korean medicine health care service that is not covered by NHIS is fairly large; therefore, a large part of Korean medicine health care utilization would not have been reported in the NHIS-NSC data [
This study analyzed the burden of disease from U codes in the year 2012 using NHIS-NSC data. Although there are some limitations, quantification of the proportion of U codes to KCD 6 codes and redistribution of those codes enable a better understanding of Korean medicine health care utilization. Furthermore, the relationship between U codes and KCD 6 codes through data visualization provides a way of understanding U code disorders and patterns from the KCD 6 perspective. Furthermore, it provided a deeper understanding of the disorders and patterns of U codes through KCD 6 diseases. This data visualization showed that musculoskeletal diseases accounted for a large part of Korean medicine utilization. Furthermore, the methodology applied in this study serves as an initial study to quantify U codes through KCD 6 codes, providing guidelines for further research of the burden of diseases, including other countries with a dual health care system similar to that in Korea.
The authors declared that there is no conflict of interests regarding the publication of this paper.
In-Hwan Oh and Bo-Hyoung Jang contributed equally to this study.
This study was supported by a grant of the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (Grant no. HI13C0729).