Krakow is the second biggest city in Poland with population exceeding 750 000 citizens. It is an academic city with 175 000 students and 22 institutions of high education. 34 000 temporary residents live there and majority of them are students. 66% of population is in working age, unemployment rate was 7% in 2005 and was one of the lowest in Poland. More than 99% of citizens are Polish, ethnic minorities form less than 1%.

Before the health care reform in 2000, doctors working in primary care in Poland were not responsible for out of hours care. For patients requiring medical help during nights the available resources were local hospitals and emergency ambulances. A new contract introduced night and weekend care. During night-time and weekends three different services are currently available, depending on the severity of the condition. GP out of hours service can deal with most minor conditions like infections or exacerbations of chronic diseases. However, patients are strongly advised to contact the service only for justified reasons, when home remedies or OTC treatment does not help and if there is a risk that delay in treatment may cause worsening of the disease. Information about local out of hours service is displayed outside each primary care practice. Hospital Emergency Departments („Szpitalny Oddzial Ratunkowy” – SOR) deal with more severe conditions. Their task include admissions, initial diagnostic and treatment of patients with urgent diseases, intoxication or injuries. Patient can attend the department without referral from family doctor or can be transported in the ambulance. In case of emergency conditions, like loss of consciousness, chest pain, seizures or dyspnoea ambulance service should be called.

Family doctors in Poland do not provide out of hours care themselves. As in other countries, they organize it in different ways [1–3]. In rural areas, far from other medical services, doctors work out of hours themselves, in a rota with their colleagues. Elsewhere they much more commonly contract those services with local hospitals and doctor-crewed emergency ambulance services. Another common form of out of hours care is to hire a commercial deputizing service which employs doctors and nurses to provide care.

Three major companies ("deputizing services") provide out of hours care in Krakow. Two companies contract the service with the practices located in the south of Krakow and one in the north. Location of the practice is the most important factor deciding which out of hours provider is used. No significant differences between population living in both parts of Krakow is observed. Altogether, in 2003–2004 there were six out of hours clinics in Krakow, with one or two doctors working in each of them and variable number of doctors doing home visits.

One of the deputizing services in the city of Krakow runs three ambulatory clinics situated in different places of the city, housed in large outpatient clinics. It provides out of hours service to 61 practices for a population of 420 000. All patients, whose family doctors have a contract with the service, have the right to use this service free of charge. They can use any ambulatory clinic, regardless of their address but most use their nearest.

Patients who call the service may request a home or clinic visit without prior triaging, although some visiting doctors speak to the patient before accepting the visit.

According to current regulations in Poland one doctor on duty should be responsible for a population not bigger than 20,000 inhabitants [4]. Exemption from this rule requires written permission from the National Health Fund – the exclusive public insurance company.

Out of hours ambulatory clinics are open from 6 pm to 8 am on weekdays and 24 hours a day on weekends and holidays. Two doctors and two nurses work in each clinic until 10 pm, one doctor and one nurse during the night. Doctors in the clinics work only on site, home visits are made by other doctors on call. Ambulatory clinics are run as walk-in clinics and patients do not make appointments. Patients are informed that waiting times for a home visit usually exceed 2–3 hours, while in the clinic they can be seen within one hour, except during seasonal increases in upper respiratory tract infections. In cases of emergency doctors or patients can call an ambulance [5].

In its present form this service has been functioning for seven years and is well known to patients. A characteristic of the service is unlimited access to primary care physicians: all patients are seen by a doctor on the same day they ask for a visit. It allows for exact assessment of daily demand for out of hours service and its periodical change.

The aim of this study is to answer the following questions: (1) To what extent does use of out of hours care depends on seasonal, weekly and daily variability? (2) What practice related factors influence the use of out of hours service by its patients? (3) What are the demographic characteristics of the patients using the service most frequently?

Our study showed significant differences in the use of out of hours care during the year. It is in contrast with data from other countries, where little variation was found [6]. Since the differences existed during two years of observation, we can exclude the influence of incidentally increased morbidity due to a seasonal epidemic. The increased number of visits during winter months is caused by a peak of viral infections. The reason for the increased number of clinic visits during months with low incidence of respiratory tract infections (May-June) needs to be established [7].

Current requirements oblige all institutions involved in out of hours care to employ a fixed number of staff (1 doctor on duty per 20 thousands inhabitants), regardless of real needs and workload [4]. This inflexible obligation is not appropriate when demand for care changes and seasonal variations exist. Although not studied here, experience from practice shows that waiting time in the clinic may be up to three hours during winter months. In a situation when no prioritization of patients is made, it may be dangerous and be one of the causes of low satisfaction with health care services in Poland. In contrast in the UK, the time taken to triage and deal with calls is strictly monitored [8].

The annual rate of contacts in our study was low when compared to British, Dutch, Danish or Irish data [9–12]. The main reason may be that out of hours care in Poland is relatively new, introduced as a standard in the whole country in 2005. Previously out of hours care existed only in the form of hospital accident and emergency departments and ambulances staffed with doctors. It was expensive and hardly accessible. Instead, many patients used private doctors for home visits and public ambulances. We can expect growth of demand for out of hours care as observed in other countries, although data from two consecutive years did not show it [13]. As patients get more acquainted with the system, utilization should also increase.

Observed inequalities in contact rates between practices from the same area may reflect differences in their organization [14, 15]. Patients having problems with accessing their own GPs during normal hours may be more likely to use the out of hours service [16, 17]. It is common for patients to come to out of hours clinic before opening hours when their medical problem should be addressed by their regular doctor. The list of health issues which may be sorted in this way is limited – it is not possible to arrange a planned referral to secondary care, patients can get prescriptions and not necessarily just urgent ones [18]. Some pharmacies are open 24 hours making it possible to request a forgotten prescription for chronic disease even in the middle of the night and this happens, especially in the case of night shift workers.

In our study for calculating the distance to the nearest out of hours clinic we used indirect method. We did it for two reasons. First, calculating the exact distance for hundreds of thousands of addresses cases was not possible with available resources and software. Furthermore, registered person's address is not always a place where he or she actually lives. There are many people who live in Krakow for years, but they still keep their previous address. Calculation of the distance from a town located 50 or 250 km from Krakow could add a bias to the practices with many non-residents registered and could lead to unreliable results.

It is well known that distance to the practice is the most important factor affecting the choice of the doctor – most of the patients register within the nearest practice [19, 20]. We can assume that majority of patients live within a walking distance to their practice. The distance from own practice to the nearest out of hours clinic may be a very good indicator of the distance between home to the clinic. This method has been used previously in other studies [21].

Our study showed the real demand for care, when not limited by the available number of daily appointments and when free for almost the entire population [22]. Out of hours clinics work on a drop-in basis, where no previous telephone appointment is required. Moreover, patients visiting the clinics in the middle of the night are more likely to be seen immediately instead of spending hours in the waiting room during peak times.

Our observations come from settings were there is no formal telephone triage, which is widely used e.q. in UK [23]. The reason for lack of telephone triage may be partly cultural. With one of the lowest number of telephones per 1000 of population in Europe, until the mid-nineties a telephone in Poland was still rather a luxury than a common household equipment. Most patients, in particular elderly ones, prefer face to face contact over telephone advice from a doctor or nurse [24].

Our study is based on observations from one city and may not reflect the situation in other regions of the country, especially in rural areas. However, with the introduction of new reporting software, such comparisons should be possible. Future studies should also include repeated observations in order to monitor the change in demand over time. The introduction of obligatory reporting with ICD-10 codes or other relevant classification expected in 2008 will be very valuable in explaining seasonal variations in contact rates and will provide scope for further, more comprehensive studies [25, 26].

We based our study on the simple database used in the service for administrative and statistical purposes. This database contained only the basic information necessary to identify the person. Since no other information (medical history, social status etc) was stored, no other analysis was possible. However, last year a new law was introduced in Poland, which allows to store medical data in electronic form only. It should give an excellent opportunity for a new research. In our future study we plan to focus specifically on the reasons for encounters and morbidity in out of hours care.

Our study confirms the existence of the group of patients who abuse out of hours services. This group is often called "frequent attenders" [27]. To some extent their behavior may be explained by practice related factors and improving access to own doctor may help to reduce the number of unnecessary out of hours visits [15]. Raising proportion of inappropriate calls to out of hours service has been reported in previous studies [28]. Our recent study showed, that three categories of ICD-10: Z00 ("general examination and investigation of persons without complaint and reported diagnosis"), Z02 ("examination and encounter for administrative purposes") and Z29 ("need for other prophylactic measures") formed almost 10% of reasons for out of hours visits. These categories are good examples of problems which should not be addressed to the emergency service [29].

Further provision of the out of hours requires some essential changes. First, information campaign for patients that out of hours service should be used only for problems, which cannot wait till own practice is open. A clear definition of such problems is necessary. Frequent reasons of encounters, like repeated prescriptions or health certificates should be excluded from this list. Patients should better understand that using out of hours care in a reasonable way is in their own interest and it can help to avoid problems with access to the GP when they really need it. For example, advice on paracetamol dosage or other antipyretics may be all that is necessary overnight for a feverish patient without other symptoms. Second, available resources should be organized with more flexible approach based on the real demand for care. Our study shows that number of calls after 10 pm decreases dramatically and most of the ambulatories can be closed at this time. To deal with late night calls less staff is required. On the other hand, staffing should be increased during seasons of increased morbidity, e.g. from upper respiratory tract infections. Out of hours performance targets should be established and waiting times should be strictly monitored. Third, implementation of telephone triage (nurse or doctor led) can limit the number of unnecessary GP visits. Observations from our study show that location of out of hours ambulatories in GP practices may lead to overuse of the service by patients from these practices. Further research is necessary to determine whether hospitals are a better place for out of hours ambulatories.