Patterns of practice in internal medicine in Ontario.

To determine the feasibility of wholly referral practice in internal medicine within a prepaid health service, the practice profiles of 694 internists in metropolitan, nonmetropolitan urban, and rural areas of Ontario were delineated by analysis of data from questionnaires and health-insurance billing. The questionnaire showed that two thirds of internists, chiefly younger practitioners, confined themselves to a referral consultant practice; the other one third included primary care. Subspecialists practised predominantly in metropolitan areas; most general internists in such areas provided primary care, whereas most general internists elsewhere had an entirely referral practice. This pattern of practice is greatly different from that in the United States but probably similar to that in other provinces in Canada. Extension of wholly referral practice to all internists in Ontario appears feasible, provided the numbers entering residency training are controlled. The present Ontario curricula for internal medicine and its subspecialties appear suitable for such a pattern of practice.     

Appropriateness of hospital referral for hypertension.

OBJECTIVE--To examine the efficiency of referral to an outpatient clinic and particularly the differences between referrals from general practitioners practising in health centres and those from other general practitioners. DESIGN--Retrospective audit of referral letters and case notes by comparison with externally set standards of appropriateness of referrals over two years. SETTING--Outpatient hypertension clinic at Western Infirmary, Glasgow. PATIENTS--306 Consecutive new referrals of patients over two years (1 May 1986 to 30 April 1988), for whom case notes were available in 298. MAIN OUTCOME MEASURES--Congruence of referrals with each of two standards of appropriateness based on published opinion on specialist referral (standard 1 was stricter than standard 2) and completeness of referral letters. RESULTS--Of the 298 referrals, those from general practitioners accounted for 205, from other hospital departments 68, and from other sources 25. Overall, 84 referrals of the 205 from general practice met the first standard and 134 met the second, more lenient standard. 58 Referral letters from outside the hospital had some item missing. Referrals from general practitioners working in health centres (a fifth of the total) were significantly more likely to meet both standards (p less than 0.01) and to send a complete referral letter (p less than 0.001) than the 145 referred by other general practitioners. CONCLUSIONS--According to the standards used, general practitioners in health centres made more appropriate referrals, and further investigation is needed to identify the underlying factors responsible.     

Referral letters and replies from orthopaedic departments: opportunities missed.

OBJECTIVE--To study delays between sending referral letters and the outpatient appointment and to assess the content of referral and reply letters, their educational value, and the extent to which questions asked are answered by reply letters. DESIGN--Retrospective review of referrals to 16 consultant orthopaedic surgeons at five hospitals, comprising 288 referral letters with corresponding replies, by scoring contents of letters. SETTING--Orthopaedic teaching hospitals in Nottingham, Derby, and Mansfield. MAIN OUTCOME MEASURES--Weighted scores of contents of referral and reply letters, assessment of their educational value, and responses to questions in referral letters. RESULTS--Median outpatient delay was 23.4 weeks. There was no significant decrease in waiting time if the referral letter was marked "urgent" but a significantly greater delay (p less than 0.01) if referrals were directed to an unnamed consultant. The content score was generally unsatisfactory for both referrals and replies, and there was no correlation for the content scores of the referral letter and its reply (r = 0.13). Items of education were rare in the referral letters (8/288; 3%) and significantly more common in replies (75/288; 26%) (p much less than 0.001). Senior registrars were significantly more likely to attempt education than other writers (p less than 0.02). Education in replies was significantly related to increased length of the letter (p less than 0.05) and was more likely to occur if the referral was addressed to a named consultant (p less than 0.03). 48 (17%) Referral letters asked questions, of which 21 (44%) received a reply. No factor was found to influence the asking of or replying to questions. CONCLUSIONS--The potential for useful communication in the referral letter and in the reply from orthopaedic surgeons is being missed at a number of levels. The content is often poor, the level of mutual education is low, and the use of the referral letter to determine urgency is deficient. Most questions asked by general practitioners are not answered.     

Influence of obstetricians' attitudes on their use of prenatal diagnosis for the detection of Down's syndrome.

Practising obstetricians were surveyed to determine the relation between their referral patterns and their knowledge and attitudes concerning prenatal diagnosis by amniocentesis for women aged 35 years and over. Although 82% had referred at least one eligible patient for prenatal diagnosis during the past year, almost none had used the available services for all appropriate patients. There was a statistically significant trend for increased referral as correct knowledge of the risks and accuracy of prenatal diagnosis increased. Moreover, a discriminant function combining risk and accuracy estimates, type and size of practice, and language distinguished the referrers from the nonreferrers (P = 0.0002), although there was considerable overlap between the physicians classified according to a high, moderate or low rate of referral. The data suggest that while knowledge and practice characteristics can distinguish obstetricians who refer patients for prenatal diagnosis from those who never do so, the frequency of referral may involve other factors, such as how physicians accept innovation and perceive risks.     

Understanding variation in rates of referral among general practitioners: are inappropriate referrals important and would guidelines help to reduce rates?

OBJECTIVES--To determine the extent to which variation in rates of referral among general practitioners may be explained by inappropriate referrals and to estimate the effect of implementing referral guidelines. SETTING--Practices within Cambridge Health Authority and Addenbrooke''s Hospital, Cambridge. MAIN OUTCOME MEASURES--Data on practice referral rates from hospital computers, inappropriate referrals as judged by hospital consultants, and inappropriate referrals as judged against referral guidelines which had been developed locally between general practitioners and specialists. Effect of referral guidelines on referral patterns as judged by general practitioners using the guidelines in clinical practice. RESULTS--There was 2.5-fold variation in referral rates among general practices. According to the specialists, 9.6% (95% confidence interval 6.4% to 12.9%) of referrals by general practitioners and 8.9% (2.6% to 15.2%) of referrals from other specialists were judged possibly or definitely inappropriate. Against locally determined referral guidelines 15.9% of referrals by general practitioners were judged possibly inappropriate (11.8% to 20.0%). Elimination of all possibly inappropriate referrals could reduce variation in practice referral rates only from 2.5-fold to 2.1-fold. An estimate of the effect of using referral guidelines for 60 common conditions in routine general practice suggested that application of guidelines would have been unlikely to reduce rates of referral in hospital (95% confidence interval -4.5% to 8.6% of consultations resulting in referral). CONCLUSION--The variation in referral rates among general practitioners in Cambridge could not be explained by inappropriate referrals. Application of referral guidelines would be unlikely to reduce the number of patients referred to hospital.     

Potential mechanisms of retronasal odor referral to the mouth

The current study took a first step toward elucidating the sensory input that drives retronasal odor referral to the mouth. In 2 experiments, subjects performed odor localization tasks under various oral-nasal stimulation conditions that allowed us to assess the effects of direction of airflow, taste, and tactile stimulation on retronasal odor referral. Subjects reported the locations of perceived odors when food odorants were inhaled through the mouth alone or in the presence of water or various tastants in the mouth. The results indicated that when perceived alone, vanilla and soy sauce odor were localized 54.7%: 26.4%: 18.9% and 60.0%: 21.7%: 18.3% in the nose, oral cavity, and on the tongue, respectively. The localization of odors alone was not significantly different from when water was presented simultaneously in the mouth, indicating that tactile stimulation itself is not sufficient to enhance odor referral. However, the presence of sucrose, but not other tastes, significantly increased localization of vanilla to the tongue. Likewise, only NaCl significantly augmented referral of soy sauce odor to the tongue. These data indicate that referral of retronasal odors to the mouth can occur in the absence of a either taste or touch but that referral to the tongue depends strongly on the presence of a congruent taste.     

Cost-Effectiveness of HIV Testing Referral Strategies among Tuberculosis Patients in India

Background

Indian guidelines recommend routine referral for HIV testing of all tuberculosis (TB) patients in the nine states with the highest HIV prevalence, and selective referral for testing elsewhere. We assessed the clinical impact and cost-effectiveness of alternative HIV testing referral strategies among TB patients in India.

Methods and Findings

We utilized a computer model of HIV and TB disease to project outcomes for patients with active TB in India. We compared life expectancy, cost, and cost-effectiveness for three HIV testing referral strategies: 1) selective referral for HIV testing of those with increased HIV risk, 2) routine referral of patients in the nine highest HIV prevalence states with selective referral elsewhere (current standard), and 3) routine referral of all patients for HIV testing. TB-related data were from the World Health Organization. HIV prevalence among TB patients was 9.0% in the highest prevalence states, 2.9% in the other states, and 4.9% overall. The selective referral strategy, beginning from age 33.50 years, had a projected discounted life expectancy of 16.88 years and a mean lifetime HIV/TB treatment cost of US$100. The current standard increased mean life expectancy to 16.90 years with additional per-person cost of US$10; the incremental cost-effectiveness ratio was US$650/year of life saved (YLS) compared to selective referral. Routine referral of all patients for HIV testing increased life expectancy to 16.91 years, with an incremental cost-effectiveness ratio of US$730/YLS compared to the current standard. For HIV-infected patients cured of TB, receiving antiretroviral therapy increased survival from 4.71 to 13.87 years. Results were most sensitive to the HIV prevalence and the cost of second-line antiretroviral therapy.

Conclusions

Referral of all patients with active TB in India for HIV testing will be both effective and cost-effective. While effective implementation of this strategy would require investment, routine, voluntary HIV testing of TB patients in India should be recommended.     

Evaluation of Genetic Consultations in the public health service

Summary Work of the Genetic Consultation Group at the Institute of Medical Genetics, USSR Academy of Medical Sciences is analyzed and evaluated from the viewpoint of working out organizational principles for counseling. During three years (from July 1973 to June 1976) 1145 families were referred to us, of which 76% were referred by physicians and 24% were self-referrals.Reasons for referral were progeny prognosis (75.7%), health prognosis (1.5%), more precise diagnosis (18.1%), treatment (2.7%), and other reasons (2%). The main cause of referral was birth of a sick child (75%). People seeking advice were divided according to disease group as follows: chromosome diseases and congenital malformations (45.4%), monogenic diseases (15.4%), diseases with hereditary predisposition (14.6%), repeated miscarriages and infertility (11.5%), and others (13.1%).For counseling, 1145 families required additional cytogenetic (987) and biochemical (138) investigations. At evaluation of genetic risk, 16 types of genetic problems were encountered.It was concluded that genetic counseling should be organized firstly in pediatric and obstetric-gynecologic services, both in general and specialized hospitals. To facilitate referrals to the consultation center, spread of genetic knowledge among physicians and the population is necessary. The most effective form of propaganda among physicians is distribution of special literature with a list of indications for referral to consultation centers; most effective among the population are articles in newspapers and magazines.     

Understanding hospital referral rates: a user's guide.

Detailed referral information from one practice was used to investigate the effect of calculating referral rates in several different ways. Referral rates for individual general practitioners should be related to the number of consultations carried out and not to the number of registered patients; for whole practices list size may be used as the denominator. Most doctors will not need to control for age and sex of patients when comparing referral rates but may need to control for case mix when comparing referral rates to individual specialties. In addition, a method is described for distinguishing systematic variation between the referral rates of individual doctors from the random variation that may arise from data based on fairly small numbers of referrals. The method indicates whether systematic variation is greater than would be expected by chance, and it can be extended to indicate whether variability in referral rates is greater in one specialty than another. Because of random variation with time a year''s data may not be sufficient to allow reliable interpretation of referral rates to individual specialties, except for the largest. At present there is no known relation between high or low referral rates and quality of care. Nevertheless, if doctors are to interpret their own rates of referral they need those rates to be reliable and valid. Use of the 10 guidelines described in this paper will help to prevent unwarranted conclusions being drawn from information on general practitioners'' rates of referral to hospital.     

Acceptability and Effectiveness of the Storekeeper-Based TB Referral System for TB Suspects in Sub-Districts of Lilongwe in Malawi

Background

Early access to tuberculosis diagnosis and treatment remains a challenge in developing countries. General use of informal providers such as storekeepers is common. The aim of this study was to determine the effectiveness and acceptability of a storekeeper-based referral system for TB suspects in urban settings of Lilongwe, Malawi.

Methods

The referral system intervention was implemented in two sub-districts. This was evaluated using a pre and post comparison as well as comparison with a third sub-district designated as the control. The intervention included training of storekeepers to detect and refer clients with chronic cough using predesigned referral letters along with monitoring and supervision. Data from a community based chronic cough survey and an audit of health centre records were used to measure its effectiveness. Focus group discussions and in-depth interviews were carried out to document acceptability of the intervention with the different stakeholders.

Results

Following the intervention, the mean patient delay appeared lower in the intervention than comparison areas (2.14 weeks (SD 5.8) vs 8.8 weeks (SD 15.1)). However, after adjusting for confounding variables this difference was not significant (p = 0.07). After the intervention the proportion of the population diagnosed with smear positive TB in the intervention sites (1.2 per 1000) was significantly higher than in the comparison area (0.6 per 1000, p<0.01) even after adjusting for sex and age. Qualitative findings suggested that (a) the referral letters triggered health workers to ask patients to submit sputum for TB diagnosis (b) the approach may be sustainable as the referral role was linked to the livelihood of the storekeepers.

Conclusion

The study suggests that the referral system with storekeepers is sustainable and effective in increasing smear positive TB case notification. Studies that assess this approach for control of other diseases along with collection of specimens by storekeepers or similar providers are needed.     

Variation in the incidence of AGUS between different patient populations

OBJECTIVE: To determine the frequency of atypical glandular cells of undetermined significance (AGUS) for three consecutive calendar years from three different referral sources. STUDY DESIGN: Cervicovaginal smears with a diagnosis of AGUS were identified from January 1995 through December 1997. The smears were submitted from three different sources: two were city government hospital clinics, one with predominantly African American and Hispanic patients and the other with predominantly Asian and Hispanic patients. The third referral source was private practitioners' offices with predominantly Caucasian patients. RESULTS: A diagnosis of AGUS was made in 707 cases, accounting for 0.56% of all smears examined. This was in contrast to 6,872 smears reported as atypical squamous cells of undetermined significance (ASCUS) (5.4%) and 3,347 reported as squamous intraepithelial lesions (SIL) or above (2.7%). The incidence of AGUS ranged from 0.16% to 1.00% among different patient populations. This difference was also noted in the rate of ASCUS and SIL in the same patient population. There was a steady increase in the rate of AGUS for each referral source during the study period. The overall rate of patients who underwent histologic evaluation and the incidence of biopsy-proven preinvasive and invasive lesions were 62.4% and 23%, respectively. There was no significant difference in the rate of significant lesions after a diagnosis of AGUS during the study period or between the three referral sources. CONCLUSION: The AGUS rate in our laboratory was low and within the range (0.17-1.83%) reported in the literature. The AGUS rate varies with different patient populations, particularly with the incidence of SIL and age distribution.     

Awareness of benign paroxysmal positional vertigo in central Israel

Background

Despite its frequent occurrence and effective treatment options, benign paroxysmal positional vertigo (BPPV) still remains under-estimated in the community.

Methods

We reviewed referral letters and medical records of 120 patients who were treated for BPPV at our Dizziness Clinic during the years 2006–2008 and searched for factors that possibly contribute to missing this entity.

Results

The referral diagnosis could be clustered into four groups: BPPV (25.6%), further unspecified vertigo (36.6%), dizziness (27.5%) and other (10%). BPPV was recognized more frequently by ENT doctors than by other specialists. Patients referred with the correct diagnosis of BPPV were significantly younger and the duration of their symptoms shorter than in other referral groups. Patients in the distinct referral groups did not differ in the presence of autonomic symptoms or a history of another serious disease. A history typical of BPPV could be obtained in all but 11 patients, but position dependence was noted by the referring physician only in 55 patients, 31 of them correctly assigned as possible BPPV. Only in two patients was the Dix-Hallpike test performed. Thirty two patients were diagnosed with BPPV in the past, but this did not influence the recognition of the recurrence of this clinical entity. About 40% of patients had an audiogram and/or brainstem auditory evoked potentials. Electronystagmography was performed in 7.5% and brain imaging in 14% of patients before referral.

Conclusion

Our results show that BPPV is still an under-recognized entity. Education and the demand on specialists to learn how to treat BPPV, could improve the situation.     

Regional variation in nonmedical factors affecting family physicians' decisions about referral for consultation

OBJECTIVE: To determine whether there is regional variation in environmental (non-medical) factors affecting referral decisions of family physicians (FPs). DESIGN: Cross-sectional interview survey. SETTING: Nova Scotia. PARTICIPANTS: A random sample of 125 FPs grouped into 1 of 5 functionally defined geographic regions of Nova Scotia (25 in each group). Groupings were based on access to general hospital beds through active staff hospital appointments or to specialist consultants in the community, or both. Participants were personally interviewed on site. No physician refused an interview. In 9 cases the physician indicated that he or she did not fit the profile of the assigned group; the physician was excluded from the study and the next doctor on the list was substituted. OUTCOME MEASURES: The questionnaire was designed to test several hypotheses about factors known to potentially influence decisions about referral. Geographic differences in factors affecting referral and in decisions about 5 hypothetical cases were assessed with the use of significance tests for proportions that were sensitive to specific orders across groups. RESULTS: Three factors affecting referral showed unequivocal variation across the 5 groups. Access to hospital facilities and remoteness from specialist care, leading to local styles of practice or treatment policies, and the FP''s relationship with specialist consultants appeared to be important nonmedical factors affecting referral decisions. For similar case scenarios the physicians living in rural areas would refer only half as often overall as those living in urban areas with tertiary care hospitals; for some cases, such as a severe asthma attack, the difference was more than 7-fold. CONCLUSIONS: Significant differences in nonmedical factors affecting referral, and in referral decisions about hypothetical cases, were found between the groups of FPs. Differences in access to resources, creating local styles of practice, appeared to explain most of the variation. The results may account for previously observed differences in actual rates of referral for these particular groups.     

Raised intraocular pressure: an alternative method of referral.

To assess delay in referring patients with suspected glaucoma two methods were studied in a randomised trial: direct referral from optician to ophthalmologist and referral through the patient''s general practitioner. Direct referral was reliable for all 49 patients involved, whereas, of the 44 patients referred through their general practitioner, seven waited over three weeks for referral.     

Inv(10)(p11.2q21.2), a variant chromosome

We present 33 families in which a pericentric inversion of chromosome 10 is segregating. In addition, we summarise the data on 32 families in which an apparently identical inv(10) has been reported in the literature. Ascertainment was through prenatal diagnosis or with a normal phenotype in 21/33 families. In the other 12 families, probands were ascertained through a wide variety of referral reasons but in all but one case (a stillbirth), studies of the family showed that the reason for referral was unrelated to the chromosome abnormality. There has been, to our knowledge, no recorded instance of a recombinant chromosome 10 arising from this inversion and no excess of infertility or spontaneous abortion among carriers of either sex. We propose that inv(10)(p11.2q21.2) can be regarded as a variant analogous to the pericentric inversion of chromosome 2(p11q13). We conclude that prenatal chromosome analysis is not justified for inv(10) carriers. In addition, family investigation of carrier status is not warranted in view of the unnecessary concern this may cause parents and other family members. Received: 7 July 1997 / Accepted: 4 August 1997     

Patterns and predictors of referral to the specialized chronic lymphocytic leukemia clinic in Manitoba,Canada

BackgroundBetter CLL patient survival has been reported for specialized CLL clinics/hematologists (compared to other CLL patients). It is possible that improved survival is driven by a better prognosis of referred patients.MethodsWe used logistic regression to calculate the odds ratios (ORs) and 95 % confidence intervals 95 %CIs) of the association between patient characteristics and CLL referral of all persons diagnosed in 2005–2016 with a pathologically-confirmed CLL or SLL.ResultsTwo-thirds of 1293 patients were referred to the CLL clinic. Referred patients were younger (16 % vs 44 % were 80 +) and in better health (47 % vs 56 % with a chronic diseases) than non-referred patients. Referral increased over time: in 2005–2010, about 60 % of patients were referred; in 2011–2016, this increased to 76 %. Gender did not affect referral (the OR for females is 1.0, 95 %CI 0.8–1.2), but age played a major role; CLL patients diagnosed at age 80 + were less likely to be referred than patients diagnosed < 60, 0.2 (0.1–0.3).ConclusionBecause referral to Manitoba’s specialized CLL clinic is associated with age and the patient’s overall health before referral, one should be careful in interpreting differences in outcomes between CLL patients based on referral status alone.     

Vision screening in preschool children: comparison of orthoptists and clinical medical officers as primary screeners.

OBJECTIVE--To see if there were differences in referral rates and abnormalities detected from two areas that were operating different preschool vision screening programmes. DESIGN--Cohort study using case notes of referrals. SETTING--Community based secondary referral centres in the county of Avon. PATIENTS--263 referrals from a child population of 7105 in Southmead district, an area that used orthoptists as primary vision screeners; 111 referrals from a child population of 2977 in Weston-super-Mare, an area that used clinical medical officers for screening. MAIN OUTCOME MEASURES--Amblyopia and squint detection rates, together with false positive referral rates. RESULTS--The amblyopia detection rate in Southmead district was significantly higher than in Weston-super-Mare (11/1000 children v 5/1000), as was the detection rate of squint (11/1000 v 3/1000). However, the false positive referral rate from Southmead was significantly lower than that from Weston-super-Mare (9/1000 v 23/1000). CONCLUSION--Preschool vision screening using orthoptists as primary screeners offers a more effective method of detecting visual abnormalities than using clinical medical officers.     

Developing a Referral Protocol for Community-Based Occupational Therapy Services in Taiwan: A Logistic Regression Analysis

Because resources for long-term care services are limited, timely and appropriate referral for rehabilitation services is critical for optimizing clients’ functions and successfully integrating them into the community. We investigated which client characteristics are most relevant in predicting Taiwan’s community-based occupational therapy (OT) service referral based on experts’ beliefs. Data were collected in face-to-face interviews using the Multidimensional Assessment Instrument (MDAI). Community-dwelling participants (n = 221) ≥ 18 years old who reported disabilities in the previous National Survey of Long-term Care Needs in Taiwan were enrolled. The standard for referral was the judgment and agreement of two experienced occupational therapists who reviewed the results of the MDAI. Logistic regressions and Generalized Additive Models were used for analysis. Two predictive models were proposed, one using basic activities of daily living (BADLs) and one using instrumental ADLs (IADLs). Dementia, psychiatric disorders, cognitive impairment, joint range-of-motion limitations, fear of falling, behavioral or emotional problems, expressive deficits (in the BADL-based model), and limitations in IADLs or BADLs were significantly correlated with the need for referral. Both models showed high area under the curve (AUC) values on receiver operating curve testing (AUC = 0.977 and 0.972, respectively). The probability of being referred for community OT services was calculated using the referral algorithm. The referral protocol facilitated communication between healthcare professionals to make appropriate decisions for OT referrals. The methods and findings should be useful for developing referral protocols for other long-term care services.     

Antimicrobial susceptibility profiles associated with bacterial meningitis among children: a referral hospital-based study in Iran

Bacterial meningitis continues to be associated with high morbidity and mortality rate worldwide, especially in the pediatric age group. This study was performed to identify the microbial etiologies of meningitis among 31 children, who were admitted in the Emergency Ward of a referral pediatric hospital in Iran. Culture identification showed that Streptococcus pneumoniae (12 subjects), Haemophilus influenzae (11 subjects) were the most common bacteria, followed by Escherichia coli (7 cases) and Neisseria meningitidis (only one case). Antibiotic susceptibility tests revealed that vancomycin had the best effect on S. pneumoniae in comparison with other antibiotics, whereas H. influenzae and E. coli were more susceptible to ceftriaxone, ceftazidime, and ceftizoxime than other antibiotics. In conclusion, despite the advances in antibiotic therapy and vaccine development, bacterial meningitis still is a health problem. S. pneumoniae, H. influenzae, and N. meningitidis are the main sources of bacterial meningitis, but other organisms such as E. coli should also be suspected, when a case is admitted to a referral pediatric hospital.     

Determining the size of a total purchasing site to manage the financial risks of rare costly referrals: computer simulation model.

OBJECTIVE: To estimate the financial risks of 15 categories of rare costly referrals for total purchasing sites of different population sizes. DESIGN: Computer simulation of 100 fund years assuming Poisson distribution of referrals. SETTING: British general practices that have opted to become total purchasing sites. Referral rates and price estimates were supplied by South and West Devon Health Commission. MAIN OUTCOME MEASURES: Variation in referral costs to purchasers in relation to size of risk pool (person years at risk). RESULTS: Random variation in referral costs increased as the size of the risk pool decreased. Variation increased greatly below 30,000 person years. The mean simulated cost of the referral categories considered was 2.8% of total NHS hospital and community service costs, and the maximum simulated cost for 7000 person years was 6.8%. Simulated variation was robust to assumption about prices and referral rates for specific types of referral. CONCLUSION: Rare costly referrals seem unlikely to bankrupt total purchasing sites. The management of risk is not in itself justification for total purchasing to be based in several general practices in order to generate large populations. There are other ways of managing risk. Sites can easily explore options by simulations using local referral rates and prices.