Prioritisation of patients on waiting lists for hip and knee arthroplasties and cataract surgery: Instruments validation

Traditionally, the only explicit system to prioritise patients awaiting surgery has been the timing of the patient's inclusion in the waiting list, although various studies show how different factors may in practise influence the waiting period [1‐3]. The lack of explicit prioritisation criteria that may cause patients with the same level of need to have very different waiting periods and the negative health effects of delay of surgery, further reinforce the necessity to develop instruments which enable the waiting list to be ordered in line with patients' needs [2, 4‐8].

Several countries, principally New Zealand, Canada and the United Kingdom, have developed prioritisation instruments as the strategy for managing waiting lists according to the needs of the patients and the benefit expected from surgery [9]. Nevertheless, most of these instruments have included doctors and other health professionals views, whereas patients' or other social groups' preferences have had little or no direct input [4, 10‐13]. In Spain, in the Basc Country and in Catalonia, prioritisation instruments for hip and knee arthroplasties and cataract surgery have been elaborated [14‐17]. In Catalonia, the prioritisation instruments developed by the Catalan Agency for Health Technology Assessment and Research (CAHTA) elicited general population, patients and close relatives, allied-health professionals and consultants preferences to establish surgical priority [16, 17].

The development of prioritisation instruments should be accompanied by an evaluation of their capacity to measure the priority of patients awaiting surgery and of their reliability. The objectives of this study were to evaluate the construct validity and inter-observer reliability of the prioritisation instruments developed by CAHTA.

This was a multicentre validation study which included patients scheduled for hip and knee arthroplasties and cataract surgery between June 2001 and June 2002 and May 2004 and March 2006 in 10 hospitals of different Spanish Autonomous Communities: 2 in Andalusia, 2 in Aragon, 2 in the Canary Islands and 4 in Catalonia. Orthopaedic surgeons and Ophthalmologists from these centres were invited to participate by recruiting and assessing the priority for surgery of their patients and answering a specific questionnaire to analyse the inter-observer reliability of the prioritisation instruments.

The total number of patients included in the study was 944 for hip and knee arthroplasties and 1,674 for cataract surgery. Table 3 shows the main characteristics of the study population.

The prioritisation instruments for hip and knee arthroplasties and cataract surgery were designed to gather information on the necessity of surgery. Although there is no gold standard for comparing the priority construct, the doctor's opinion on surgical priority (VAS) and the patients' perception of the difficulty caused by the condition and HRQOL could be the nearest approximation. The strong correlation observed in the convergent analysis between the doctor's opinion on surgical priority (VAS) and the overall priority score indicates that the AI and CI are collecting the relevant aspects that doctors take into consideration when assessing the need for surgery. However, correlations with doctors' opinions were not higher because the criteria included in the prioritisation instruments and their scores not only reflect the opinion of medical specialists, but also of general population, patients and close relatives and allied-health professionals [16, 17]. On the other hand, the prioritisation instruments include criteria related to patients' self-perception that could have also influenced the correlation between the overall priority score and doctors' opinion (VAS).

The disease specific HRQOL questionnaires, WOMAC and VF-14, and the patients' perception of the difficulty caused by their condition were also among the aspects that most strongly correlated with the overall priority score. This suggests that the prioritisation instruments are also able to collect patients' perceptions about how aspects of their daily life have been affected by their condition. Nevertheless, generic and specific HRQOL questionnaires measure self-perceived health status and functional capacity, while priority instruments include additional aspects such as to have someone to look after the patient or to be a care-giver. This could justify the moderate correlations found, since HRQOL is only part of the priority construct and not its whole constituent. On the other hand, generic HRQOL instruments show little influence by specific diseases such as cataracts. The unexpected weak correlation between the overall priority score of the AI and the anxiety/depression EQ-5D dimension, could be due to the association between mood disturbance and pain and disability among people living with hip and knee osteoarthritis. However, this weak correlation was not observed between the overall priority score of the AI and the dimension on emotion of the HUI3, which also gathers information on anxiety and depression.

In New Zealand and Canada the results from the validation of their prioritisation instruments were similar to those of this study, even though the method followed in their development was different from that of CAHTA's instruments, which reinforces their validity [4, 10]. In New Zealand the AI presented weak correlations both with the EQ-5D (0.23) and with the WOMAC (0.26) [24, 25, 32]. For the CI, the correlations between the priority score and the opinion of the specialist measured through a VAS (0.41) [33] and the VF-14 (0.45) were moderate, and low (0.22) for the EQ-5D [24, 25]. In Canada the correlation found between the AI and the opinion of the specialist measured by VAS was strong (0.79), and moderate with the EQ-5D (0.33) and the WOMAC (0.33). In the case of the CI, the correlation with the opinion of the specialist was strong (0.65), weak with the EQ-5D (0.16), and moderate (0.35) with a modified version of the VF-14 [26, 27].

The degree of agreement between doctors when evaluating different hypothetical scenarios with the prioritisation instruments was acceptable. Both instruments presented inter-observer reliability values considered appropriate for group comparisons, but the priority score should be interpreted cautiously at the individual level. Although the variability in assessing the priority of patients might exist, overall health resources would be assigned first to those who need them most. In the case of Canada the results were again similar to those found in our study. The ICC for each of the seven criteria of the prioritisation instruments for hip and knee arthroplasties ranged from 0.56 to 0.81 [12].

Limitations of the study include the use of two different sources of information to validate the prioritisation instruments – the doctor and the patient- and doctors answering the VAS as well as administering the prioritisation instrument. The results could have been influenced by the quality of doctor-patient communication and by the perception of each about the health status and functional limitations. In any case, prioritisation instruments are intended to be used in the clinical setting and the correlations observed between the prioritisation instruments and the HRQOL questionnaires, show that doctors are reflecting patients' perceptions in the prioritisation instruments. The fact that doctors answered the VAS and also administered the prioritisation instrument may have affected the results on the correlations between the VAS and the prioritisation instruments, but they were similar to other studies. On the other hand, the lack of information on the doctor who assessed the priority has made it impossible to analyse the variability of the VAS assessments, as was done in New Zealand [33].

The process of patients' recruitment, doctors' participation and the time elapsed between patients' recruitment and the telephone interview are also limitations of the study. Patients were probably not consecutive. However, the priority distribution was similar to that available at the Catalan Health Service for patients in waiting list. In addition, workload was the main reason why a patient was not included in the study which could be assume as a random selection of patients. Not all the doctors invited to participate finally collaborated in the study. If participating doctors collected information in a more accurate manner than would have done the rest of the doctors, our results could have been biased towards higher correlation coefficients and differences between the levels of the priority criteria. On the contrary, the time elapsed between patients' recruitment and the telephone interview might have reduced correlation coefficients. Doctors' perception on patients' functional limitations and pain could have diverged as time went on.

Regarding the reliability analysis, the use of hypothetic scenarios may represent a limitation as it involves a simplified form of real prioritisation. The scenarios had a limited number of patients' characteristics to keep it manageable for participants, which impedes the analysis of patients' characteristics that might have influenced priority assessment. Besides, the scenarios stated clearly which were the patients' priority profiles avoiding other factors that may influence doctor-patient communication during the medical visit, as the influence that patients' requirements and attitudes might have had over doctors' priority assessment. This could have increased the estimation of the prioritisation instruments ICC.

The development of prioritisation instruments could be a time-consuming task, which might induce the utilisation of more simple and quick-to-administer instruments. The strong correlation noted both for the CAHTA's AI and CI with the doctor's opinion on surgical priority could justify VAS utilisation as an alternative prioritisation instrument. Moreover, in Canada the VAS showed an inter-observer reliability of between 0.70 and 0.82 similar to that of CAHTA's AI and CI [12]. However, using this kind of instruments does not make explicit the criteria used to determine the need for surgery, and the instruments themselves may show significant variability [33]. The main contribution of the prioritisation instruments is a greater transparency in the management of waiting lists which may increase trust in the health care system among the general population. Moreover, the inclusion in the prioritisation instruments not only of medical specialists opinions, but also the preferences of general population, patients and close relatives and allied-health professionals, may increase the acceptability of these type of instruments.

The validity of the AI and CI seems acceptable. Besides their construct validity and reliability, the method followed to develop them assures a good content validity, and they also showed an adequate internal validity being able to discriminate between different patients' priority profiles [16, 17]. However, there are other important aspects to take into consideration before their implementation. Routine use in the clinical setting requires the instrument to be manageable. Although simplicity could threaten validity, a prioritisation instrument with few criteria reduces the possibility of missing information on some of them. On the other hand, the inclusion in the prioritisation instrument of many criteria usually assessed during the medical visit may reduce the burden of its administration. Nevertheless, the utilisation of these prioritisation instruments could be sometimes difficult. All health professionals and managers must be involved in their implementation. It could be also necessary to supervise its application to prevent distortions in the priority assessment – an inflation of the priority score could happen once patients know which are the criteria used to order the waiting list or doctors could increase the priority of their patients to justify their inclusion in the waiting list-, and it has to be set up as an information system able to both incorporate and apply this new information. However, it is important to highlight that both hip and knee arthroplasties and cataract surgery are surgical interventions that have proved their worth in our society, so that reducing the waiting time for those who most need the surgery implies a significant reduction in the overall burden of impairment and disease [34]. Such a reduction of the burden among the general population could assist families and reduce the costs both of the medical attention required and of the different kinds of social benefits.

The findings show acceptable validity and reliability for prioritisation instruments in determining the overall priority of a patient awaiting surgery with a high degree of agreement between evaluators. Using prioritisation instruments can bring important improvements in the management of waiting lists.