Search strategy
In the present study, we followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement [
8]. We searched six databases (PubMed, the Cochrane Library, Google Scholar, Ichushi-Web, JDreamIII and CiNii) for studies in Japan coded by ICHPPC and ICPC up to March 2015. The search strategy was based on the following title/abstract keywords in English and Japanese: (“ICPC” OR “ICPC-2” OR “ICHPPC” OR “International Classification of Primary Care” OR “International Classification of Primary Care-2” OR “International Classification of Health problem in Primary Care”) AND (“Japan”). We also reviewed the reference lists of relevant studies to identify research that might have been missed in the database search.
Ichushi-Web is an online Japanese literature searching system provided by the non-profit Japan Medical Abstracts Society. Ichushi-Web covers about 10 million medical papers from 6000 journals in Japan, and is often used for Japanese literature searches [
9].
JDreamIII (Japan Science and Technology Agency Document Retrieval System for Academic and Medical Fields) is an online Japanese literature searching system provided by the Japan Science and Technology Agency. JDreamIII covers about 60 million articles, including serial publications, reports, conference material, public documents and proceedings on science and technology [
10].
CiNii is an online Japanese literature searching system provided by the National Institute of informatics. CiNii covers about 18 million articles focusing on natural and cultural science [
11].
Inclusion and exclusion criteria
Literature searches and data extraction were independently conducted by two investigators (M.K. and R.O.), and any discrepancies were resolved by discussion. In the present study, databases were searched for observational studies in Japan coded by ICHPPC, ICHPPC-2, ICHPPC-2-Defined, ICPC and ICPC-2 classifications to evaluate the correlation between patients’ RFEs and health problems and population density. Studies conducted in the hospital setting were excluded because the aim of the study was to clarify the spectrum of RFEs and health problems in primary care. Details of the inclusion criteria are shown in Table
1.
Table 1
Inclusion criteria
Date of publication | Until March 31, 2015 |
Setting | Japan |
| Clinic only (Hospital were excluded) |
Methods | Coding RFEs or health problems using ICHPPC, ICHPPC-2, |
| ICHPPC-2-Defined, ICPC and ICPC-2 |
Results | Frequency of RFEs and health problems |
The present study included the following classifications developed by the World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians (WONCA) [
6]:
ICHPPC: Developed in 1975 to classify health problems in primary care. The classification was mapped to ICD-8.
ICHPPC-2: Developed in 1979 and mapped to ICD-9.
ICHPPC-2-Defined: Developed in 1983. Explanatory remarks were added with ICHPPC-2 to improve usability.
ICPC: Developed in 1987 to combine “Reasons for Encounter Classification (RFEC)” and “International Process in Primary Care (IC-Process-PC)” with the ICHPPC. The classification contained RFEs, including feelings of patients and interventions. The classification was mapped to ICD-10.
ICPC-2: Developed in 1998 and mapped to ICD-10. Explanatory remarks were added with ICPC. This classification is frequently used in primary care settings all over the world. It has been translated into 22 languages.
Studies that did not mention the frequency of RFEs and health problems, studies conducted in countries other than Japan, unpublished data, conference presentations, and conference minutes were all excluded from the present study.
Extracted information is shown in Table
2. In Japan, patients who have “non-internal medicine-related” RFEs tend to visit specialists as opposed to internists [
3]. Therefore, a high percentage of “non-internal medicine-related” RFEs and health problems is thought to indicate the comprehensiveness of RFEs and health problems by the primary care physician. To clarify the comprehensiveness of RFEs in Japanese primary care settings, we calculated the proportions of“non-internal medicine-related RFEs” and “non-internal medicine-related health problems” among the top 20 RFEs and health problems in each study because most of included studies did not report the rank of RFEs and health problems more than the top 20.
Year of publication | |
Author | |
Setting | The categories of setting are based on description in each included study |
Study period | |
Number of facilities | |
Total number of patients | |
Total number of encounters | |
Total number of RFEs | |
Total number of health problems |
Proportion of “non-internal medicine-related” RFEs in the top 20 RFEs |
Proportion of “non-internal medicine-related” health problems in the top 20 health problems |
Classification | ICHPPC/ICHPPC/ICHPPC-2-Defined |
| ICPC/ICPC2 |
Primary outcome measures | RFEs (first visit, periodic visit)/health problems (acute, chronic) |
Distinction between acute and chronic |
Quality of coding | Prospective or retrospective |
| Single or multiple evaluator |
| Description of coding training |
Prospective or retrospective |
Number of evaluators | |
Eighteen categories of health problems in the ICHPPC: Among these categories, “I: Infective and parasitic,” “II: Neoplasms,” “III: Endocrine, nutritional and metabolic” “IV: Blood disease” “VI: Nervous system and sense organs,” “VII: Circulatory system,” “VII: Respiratory system,” “IX: Digestive system,” were defined as “internal medicine-related”. In contrast, “V: Mental disorder,” “X: Genitourinary system(including breast),” “XI: Pregnancy, childbirth and puerperium,” “XII: Skin and subcutaneous tissue,” “XIII: Musculoskeletal and connective tissue,” “XIV: Congenital anomalies,” “XV: Perinatal morbidity,” “XVII: Injuries and adverse effects,” were defined as “non-internal medicine-related”. (“XVI: Signs, symptoms and ill-defined conditions,” and “XVII: Supplementary” were excluded.)
Seventeen categories of RFEs and
health problems in
the ICPC (Table
3): Among these categories, “A: General and unspecified,” “B: Blood. Blood-forming organs and immune mechanism,” “D: Digestive,” “K: Cardiovascular,” “N: Neurological,” “R: Respiratory” and “T: Endocrine/Metabolic and Nutritional” were defined as “internal medicine-related”. In contrast, “F: Eye,” “H: Ear,” “L: Musculoskeletal,” “P: Psychological,” “S: Skin,” “U: Urological” “W: Pregnancy, Childbearing, Family Planning,” “X: Female genital,” “Y: Male genital” and “Z: Social problems” were defined as “non-internal medicine-related”.
A: General and unspecified | A01 Pain general/A02 Chill/A03 Fever |
B: Blood. Blood-forming organs and immune mechanism | B02 Lymph gland/B04 Blood symptom/B25 Fear of AIDS |
D: Digestive | D01 Abdominal pain/D02 Abdominal pain epigastric/D03 Heartburn |
F: Eye | F01 Eye pain/F02 Red eyes/F03 Eye discharge |
H: Ear | H01 Ear pain/H02 Hearing complaint/H03 Tinnitus |
K: Cardiovascular | K01 Heart pain/K02 Pressure/K03 Cardiovascular pain |
L: Musculoskeletal | L01 Neck symptom/L02 Back symptom/L03 Low back symptom |
N: Neurological | N01 Headache/N02 Face pain/N04 Restless legs |
P: Psychological | P01 Feeling anxious/P02 Acute stress reaction/P03 Feeling depressed |
R: Respiratory | R01 Pain respiratory system/R02 Shortness of breath/R03 Wheezing |
S: Skin | S01 Pain of skin/S02 Pruritus/S03 Warts |
T: Endocrine/Metabolic and Nutritional | T01 Excessive thirst/T02 Excessive appetite/T03 Loss of appetite |
U: Urological | U01 Dysuria/U02 Urinary frequency/U04 Incontinence Urine |
W: Pregnancy, Childbearing, Family planning | W01 Question of pregnancy/W02 Fear of pregnancy/W03 Antepartum bleeding |
X: Female genital | X01 Genital pain female/X02 Menstrual period/X03 Intermenstrual pain |
Y: Male genital | Y01 Pain penis/Y02 Pain in testis/Y03 Urethral discharge |
Z: Social problems | Z01 Poverty/Z02 Food or water problem/Z03 Housing problem |
We were not able to find the definition on the distinction between “internal medicine-related” and “non-internal medicine-related” in the previous reports. Therefore, two of authors, (MM and MK), a Fellow of the Japanese Society of Internal Medicine and a Japan Primary Care Association certified family physician, discussed and defined this distinction for the study. In detail, we discussed which clinical speciality was mainly chosen by patients having the RFEs of each ICPC/ICHPPC- chapter under the situation that both internists and other specialists such as ophthalmologists were equally available. Also, we took into consideration whether an internist referred a patient to specialists.
Statistical analysis
Usual indicators of accessibility such as “Provider-to-population ratios”, “Travel impedance to nearest provider” and “Average travel impedance to provider” [
12] could not be evaluated from the studies conducted in the past and past census data. That was the reason why we employed population density as an index of accessibility, because population density can be used as an indicator of rurality [
13]. We then calculated Spearman’s rank correlation coefficient to examine the correlation between the proportion of “non-internal medicine-related” RFEs and health problems in each study area in consideration of the population density.
We calculated the population density in each study based on census data in the administrative district area from the year closest to the study period [
14,
15].