The spectrum of skin‐related conditions in primary care during 2015–2019–A Finnish nationwide database study

Summary Background Skin‐related conditions are the frequent cause of doctors’ consultations in primary care. Methods Based on nationwide data bank information of the Finnish Institute for Health and Welfare, we analysed the 20 most frequent main diagnoses for each ICD‐10 category of all general practitioners’ visits in the public health care in Finland over the years 2015–2019. Results The total amount of doctor’s visits was 19 204 613 of which 1 489 228 consultations (7.80%) had a skin‐related condition as the main diagnosis. The most frequent skin‐related conditions were eczematous eruptions, bacterial skin infections and benign skin neoplasms accounting for 749 351 consultations (50.32%). The spectrum of skin‐related conditions was diverse, with a large quantity of rarer diagnoses. Some diagnoses showed significant proportional changes. Conclusions The results demonstrate that a limited amount of conditions comprises most of the skin‐related consultations in primary care in Finland. Undergraduate education in dermatology should concentrate on the most frequent conditions seen by general practitioners, but also address the wide range of skin problems.


| INTRODUCTION
Skin-related conditions are frequent consultation causes in primary care. 1,2 Regardless of the geographical location or structure of the health care system, skinrelated conditions are among the most frequent diagnoses of general practitioners' visits. 3,4 A limited amount of diagnoses seems to dominate, but the spectrum of skin-related conditions is wide. 5 Based on nationwide database information, we aimed to investigate the most frequent skin-related conditions seen by general practitioners in Finland and analyse their proportional changes over the years 2015-2019. In addition, we wanted to evaluate what proportion skinrelated conditions account for in primary care. In light of these results, we wanted to discuss if undergraduate training in dermatology concentrates on the correct conditions and if resources are directed adequately to dermatology compared with other medical specialities.
doctor's visit and has been digitally collected since 2015. The health care of Finland consists of a decentralised three-level state-funded health care system and a markedly smaller private sector. Its basic components are a large public primary care and the secondary and tertiary specialist health care (central and university hospitals). Doctor's consultations in primary care are open to all citizens and free of charge. Primary care doctors are able to consulate the state organised specialist care or send the patient for specialist referral.
Search criteria for the analysis were doctor's visit (main cause or diagnosis of actual consultation) and outpatient visit in primary care (mostly health centre). All age groups (0-99 years) and both sexes were included in the database search. Results for all Finnish municipalities were included. We searched for skinrelated conditions based on ICD-10 classification codes: Diseases of the skin and subcutaneous tissue (L00-L99), skin related infections (A00.0-B99.9), skin neoplasms (D22, D23, D17, D18, C43-C44) and other skin-related diagnoses (e.g. congenital malformations Q82). The investigated database includes the 20 most frequent diagnoses for each ICD-10 category (e.g., category L00-L99). The remaining more infrequent diagnoses are grouped under 'other diagnoses'. Subgroup diagnoses (i.e., L20.0) are not distinguished. Presented numbers signify absolute amounts of consultations in which a given diagnosis was the main cause of the general practitioner's visit.
The proportional changes of the skin-related conditions were analysed with the IBM SPSS Statistics 25.0 program. Differences in proportions were compared with the z-test and p values < 0.05 were considered statistically significant.  (Table 1).

| Characteristics of the database search
Of the total amount of doctors' visits, there were 1 489 228 (7.80%) consultations with a skin-related condition. The 20 most frequent skin-related conditions were the main diagnosis in 1 113 896 consultations, comprising 74.50% of doctors' visits with a skinrelated condition. There was a significant variation of diagnoses and the spectrum was diverse, with a large quantity of rarer diagnoses. The database included information of different ICD-10 categories and in total, there were 42 diagnoses recognised as skin-related conditions. These accounted for 1 278 113 consultations (85.82%). In addition, there were 211 115 consultations (14.18%) with a diagnosis classified as 'other skin-related conditions'. This group was not What is already known about this topic?
� Skin-related conditions are frequent in primary care. Skin infections, eczematous eruptions and benign skin neoplasms seem to dominate, but there is a limited amount of prevalence data available.

What does this study add?
� The study provides a comprehensive picture about the spectrum of skin-related conditions in primary care in Finland. � Undergraduate dermatology training should both concentrate on frequent conditions but also address the great variety of skin-related conditions.  differentiated more in the databank, but is likely to include important dermatological problems such as contact dermatitis or rosacea.
Benign skin neoplasms were a frequent cause of doctors' consultations: melanocytic nevi (92 013 consultations, 6.18%), seborrhoeic keratosis (83 743, 5.62%) and other benign skin neoplasms (34 911, 2.34%). Malignant neoplasms of the skin were the main diagnosis in 16 823 doctor's visits (1.13%). This group did not include cutaneous melanoma (C43) which was not under the 20 most frequent diagnoses in the category C00-D49. Nail diseases were among the most frequent consultation causes (53 617, 3.60%). The group includes ingrown toenail, nail changes and dystrophy, but not paronychia (L03.0) which is included in the cellulitis diagnosis code.

| DISCUSSION
The results of this nationwide database study demonstrate that a limited amount of diagnoses comprises most of the skin-related conditions in primary care in Finland. The most frequent being skin infections, eczematous eruptions and benign skin neoplasms. 8,9 We think that undergraduate training in dermatology should concentrate on providing a strong basis of practical and theoretical knowledge of frequent skinrelated conditions. 10,11 In addition, the database analysis shows the wide spectrum of skin-related conditions, which should also be addressed in training of medical students. 12,13 Schoefield et al. analysed surveillance data for 2006 and showed that skin conditions were the commonest new presenting reason to general practitioners in England and Wales. 1 The study data revealed that skinrelated conditions accounted for 24% of all consultations. There was no evidence of increasing or decreasing trends during 2006. Kerr et al. investigated all skin-related consultations during a 2-week period in 13 selected general practices in Edinburgh and Lothian in Scotland. 5 Similarly, skin-related conditions were the most frequent cause of doctors' visits, accounting for 18.8% of all consultations. In both studies, the most frequent were skin infections, eczematous eruptions and benign skin neoplasms, very similar to our study data. The relative amounts in our data were lower: skinrelated conditions accounted for 7.80% of doctors' visits in primary care. The lower proportion compared to previous studies might be explained by the limited information of the investigated database in which only the main diagnosis was documented. The diagnosis of a patient´s major chronic disease, for example diabetes, is often documented as the reason of consultation in primary care and therefore the real amount of skinrelated conditions may be underestimated. 11 Nevertheless, our understanding of the spectrum of skin-related conditions in primary care remains uncomplete. 1,3,5 It is likely to differ substantially from that of specialist care. Buendía-Eisman et al. found that the most common diagnoses recorded by Spanish dermatologist in outpatient clinics were actinic keratosis, basal cell carcinoma and melanocytic nevus. 14 González-Cruz et al. investigated referrals from primary care to dermatologists and found that 31.6% were for cystic lesions or benign tumours and so potentially avoidable. 15 Many patients (22%) could be discharged on the first visit; in these cases, the most frequent diagnoses were seborrhoeic keratosis (9.3%) and melanocytic nevus (8.6%). The results underline the importance of benign skin neoplasms in primary care, which was also observable in our data although we did not analyse referrals to specialist care. Doctors' visits in primary care usually include a wide range of problems and aim to acquire a holistic view of the patients' health. Skin-related conditions are often addressed alongside other complaints. 16 Thus, they are more likely to be left undocumented as separate diagnoses. Salvi et al. found in a 1-day point prevalence study in India, that skin-related conditions were the third most frequent consultation cause in primary care (prevalence 9.0%) after gastrointestinal disorders (prevalence 25.0%) and cardio-vascular disorders (prevalence 12.5%). 3 Skin-related conditions seem to be frequent in primary care independently of the geographical region or structure of the health care system. 17 Our results show that the spectrum of skin-related conditions in primary care in Finland is diverse. There were three most frequent diagnosis groups, a range of  information, it probably includes frequent dermatological problems of the general population, for example contact dermatitis (L23-L25), hair diseases (L63-L68) and rosacea (L71). The proportions of the most frequent skin-related conditions did not change significantly during 2015-2019. Significant changes seen in some ICD-10 codes with relatively small total amounts might be based on normal fluctuation. The decrease of varicella is likely to be explained by the introduction of the varicella vaccination to the national vaccination program in autumn 2017. 18 Decrease of the proportion of insect stings, angioedema and anaphylaxis, chlamydial STD and molluscum contagiosum may be caused by changes in documentation codes and habits. The increase of nail diseases and seborrhoeic keratosis might be linked to changes in demographic structure and ageing of the population. The prevalence of bullous pemphigoid 19 and chronic lower limb ulcer 20 seems to be increasing in developed countries, and our data shows this trend in the primary health care of Finland.

Skin-related diagnosis and ICD
The main limitation of this study was classification bias. Diagnoses were not verified by dermatologists, and this could have led to classification bias and explain the lower proportions of relatively common diseases in dermatologic outpatient setting such as rosacea, contact dermatitis or hidradenitis suppurativa. In addition, the data includes only information about doctors' visits, but not nurses' or other health care specialists' consultations, which can be extensive in primary care. 21 Eczematous eruptions (L30) was the most frequent skin-related diagnosis, but the amount of consultations might be overestimated, because often contact dermatitis is classified under eczematous eruptions (L30). In addition, the code L30.9 is frequently used to classify unknown or unspecific skin eruptions and not always consequently. Diagnosis codes for skin infections are frequently documented (bacterial, viral or fungal infections) without microbiological verification and other skin-related conditions may have been classified as infections. We analysed data for the whole country and there might be differences in geographical distributions. A recognised limitation of the study was also, that skin-related subgroup diagnoses (e.g., L30.0 for nummular dermatitis) could not be analysed.
The results of this nationwide database study show that three groups dominate the skin-related problems seen by doctors' in the Finnish primary health care. The study included a very large number of analysed doctors' visits in the public primary health care sector and provides a comprehensive picture about the spectrum of skin-related conditions that general practitioners encounter in Finland. The great variety of skin-related conditions in primary care was also observable. The diversity of skin-related conditions makes the diagnosis, differential diagnoses and management challenging, especially for doctors' in training. [22][23][24][25] We therefore believe that it would be important in undergraduate teaching to both concentrate on frequent conditions but also address the wide range of skinrelated problems in primary care. 26,27 Dermatology represents a small clinical speciality in medical school, and thus training of skin-related conditions is often very limited. 28,29 As a future perspective, we think that more studies are needed to address the question if resources of medical training are directed adequately to dermatology compared with other medical specialities. 30,31