Measures of gain in certainty from a diagnostic test

The authors propose several measures for quantifying the change in the clinical estimate of a patient's chances of having a disease that occurs as a result of diagnostic testing. Under most circumstances, the gain in clinical certainty from a positive test result is more affected by the specificity (T) of the test, while the gain from a negative test result is more affected by sensitivity (S). The prevalence of the disease in the tested population is also an important determinant of the magnitude of gain in certainty. Measures of the expected gain in certainty can be calculated by weighting the gains from a positive or negative result by the likelihood of the respective test outcome. Indices of expected gain depend directly on the quantity S + T, implying that sensitivity and specificity have equal importance in determining expected gain. When S + T = 1, the test provides no information; when S + T is greatest, the expected gain is maximized. Expected gain is also related to the receiver operating characteristic curve for a diagnostic test: the point on the receiver operating characteristic curve at which S + T is greatest corresponds to the point at which the distance from the major diagonal is greatest at which the slope of the receiver operating characteristic curve equals 1.     

Nurse practitioner and physician adherence to standing orders criteria for consultation or referral.

The degree to which nurse-practitioners (NPs) and physicians (MDs) follow the mutually agreed-upon rules for their practice and the effects of any deviations are unknown. This study assessed whether NPs adhered to consultation/referral (C/R) criteria in NP standing orders for hypertension, whether MDs adhered to the task-delegation intent expressed in standing orders, and the relationship between adherence and blood-pressure (BP) control. A sample of 161 patients from a practice of five MDs and four NPs in a rural primary care clinic was studied over 16 months. Patient characteristics associated with provider non-adherence were identified by discriminant analysis. NPs failed to obtain consultation or referral for 22 of 66 patients (33 per cent) with conditions requiring C/R. MDs retained 17 of the 43 patients (40 per cent) without C/R conditions. NP non-adherence was associated with care by a single NP, presence of few non-hypertension problems, and need for dietary alteration (p less than .05). MD non-adherence was associated with males and presence of severe non-hypertensive disease (p less than .005). Diastolic BP control (less than or equal to 90 mm Hg) was similar in NP patient groups without C/R conditions, retained by NPs despite C/R conditions and shared with MDs by C/R. Control in the shared group was better than in the MD-treated group with C/R conditions (p less than .025). Although in this setting NPs frequently did not adhere to C/R criteria for hypertension, this did not affect acceptable BP control.     

Variability in GPs' referral rates in Spain

The purpose of this study is to explore the causes that mayinfluence the variations on referral rates in a sample of 242general practitioners (GPs) in Spain. We applied Poisson multivariant regression modeling to analyzethe role played by different variables related to doctors, patientsand practices. The mean referral rate was 6.92±0.22 with a variant coefficientof 50.6%. The results of the Poisson model showed a statisticallysignificant variation on the following variables: 1) doctorgender; 2) proportion of consultations to the practice madeby male patients; 3) proportion of consultations made by patientsover 65 years of age; 4) list size, 5) number of doctors inthe PCT; 6) number of practice consultations to each doctorper week; 7) accredited practice for VT; 8) location of practice;9) proportion of outpatient referrals; 10) proportion of privatereferrals; 11) proportion of emergency referrals; 12) proportionof referrals in which the patient's attitude did not influencethe doctor for the referral; 13) proportion of new referrals. The statistical significance for the final model was very high(P < 0.00001). The study draws attention to the influence of some structuralcharacteristics of health care system on the referral ratesthat could be modified to reduce the number of referrals fromPrimary to Secondary Care.     

Technology, medicine & health, Part 2. The dilemmas of diagnostic certainty

In Part 1 of this series we discussed how it is that our new understandings of biology at the molecular level are revealing to us unexpected complexities in those processes labeled as diseases. Here in Part 2 we examine some remarkable ultra-sensitive tools with which it is becoming feasible to clarify these complexities with degrees of certainty heretofore regarded as impossible.     

A reliability study of an instrument for measuring general practitioner consultation skills: the LIV-MAAS scale.

OBJECTIVE: To evaluate the reliability of a new tool, the LIV-MAAS, in assessing consultation competence in UK general practice. DESIGN: These were pilot studies, with small numbers of participants. Videoed general practitioner (GP) consultations were analysed by trained lay and professional raters, using the LIV-MAAS. The inter-rater reliabilities were assessed. Four videos were assessed by five raters in a pilot study. After this, 71 consultations from eight doctors were assessed by sets of three raters. MAIN MEASURES: Inter-rater reliabilities and inter-consultation reliabilities. RESULTS: For the pilot study, the estimated inter-rater reliability ranged from 0.69 (one rater) to 0.91 (five raters). For the main study, the estimated inter-rater reliability for the LIV-MAAS checklist using two raters was 0.71, and using three raters it was 0.78. Mean differences in reliability within each series of nine consultations were 0.20 (three raters) and 0.42 (two raters). CONCLUSIONS: As a measure of 'consultation competence', administered by trained raters (medical or lay) to real GP consultations, the LIV-MAAS instrument shows adequate reliability and stability but would benefit from considerable shortening. Further development of the LIV-MAAS and testing with larger samples are required.     

General practitioner provision of preventive child health care: analysis of routine consultation data

ABSTRACT: BACKGROUND: GPs contribute to preventive child health care in various ways, including provision of child health surveillance (CHS) reviews, opportunistic preventive care, and more intensive support to vulnerable children. The number of CHS reviews offered in Scotland was reduced from 2005. This study aimed to quantify GPs' provision of different types of preventive care to pre-school children before and after the changes to the CHS system. METHODS: GP consultation rates with children aged 0-4 years were examined for the 21/2 years before and after the changes to the CHS system using routinely available data from 30 practices in Scotland. Consultations for CHS reviews; other aspects of preventive care; and all reasons were considered. RESULTS: Prior to the changes to the CHS system, GPs often contributed to CHS reviews at 6-8 weeks and 8-9 and 39-42 months. Following the changes, GP provision of the 6-8 week review continued but other reviews essentially ceased. Few additional consultations with pre-school children are recorded as involving other aspects of preventive care, and the changes to CHS have had no impact on this. In the 21/2 years before and after the changes, consultations recorded as involving any form of preventive care accounted for 11 % and 7.5 % respectively of all consultations with children aged 0-4 years, with the decline due to reductions in CHS reviews. CONCLUSIONS: Effective preventive care through the early years can help children secure good health and developmental outcomes. GPs are well placed to contribute to the provision of such care. Consultations focused on preventive care form a small minority of GPs' contacts with pre-school children, however, particularly since the reduction in the number of CHS reviews.     

Variability and consistency of rates of primary and repeat cesarean sections among hospitals in two states.

Hospitals in New York and Illinois have wide variations in their primary and repeat cesarean section rates. A number of factors account for these differences. To investigate whether hospitals with higher or lower rates tend to continue these patterns over time, their rates in 1988 were compared with those in 1983. It was found that a hospital''s cesarean section rate was consistent, but some regression to the mean process did occur. By 1988, teaching hospitals had lower rates than nonteaching hospitals; this difference is likely due to the greater response to calls for increasing trials of vaginal birth after a previous cesarean section by teaching hospitals. Over time this should contribute to further moderating of the rates. Data were from the Illinois and New York State Departments of Health.     

Nutritional screening and dietitian consultation rates in a geriatric evaluation and management unit

Aim

Nutritional screening may not always lead to intervention. The present study aimed to determine: (i) the rate of nutritional screening in hospitalised older adults; (ii) whether nutritional screening led to dietitian consultation and (iii) factors associated with malnutrition.

Methods

In this prospective study of patients aged ≥70 years admitted to a Geriatric Evaluation and Management Unit (GEMU), malnutrition was screened for using the Mini Nutritional Assessment Short Form (MNA‐SF) and identified using the Mini Nutritional Assessment (MNA).

Results

Of the 172 patients participating in the study, 53 (30.8%) patients were malnourished, and 84 (48.8%) were at risk of malnutrition. Mean (SD) age was 85.2 (6.4 years), with 131 patients (76.2%) female. Nutritional screening was performed for all patients; however, it was incomplete in 59 (34.3%) because of omission of the anthropometric measurement. Overall, 62 (36.0%) of the total number of patients were seen by the dietitian, which included 26 (49%) of malnourished patients, 27 (32%) of at‐risk patients and 9 (26%) of the well‐nourished patients. No patients lost >1% of body weight during GEMU stay. Malnourished patients were more likely to be frail, have poor appetite, depression, and have lower levels of: albumin, cognition, physical function, grip strength and quality of life.

Conclusions

The full benefits of nutritional screening by MNA‐SF may not be realised if it does not result in malnourished patients receiving a dietitian consultation. However, it is possible that enrichment of the foodservice with high protein/high‐energy options minimised patient weight loss in the GEMU.     

Activities of a consultation and diagnostic polyclinic for AIDS and AIDS-related infections

The analysis of curative and diagnostic work of AIDS counselling and diagnostic units (CDU) showed that during a year and a half 15,000 people had been screened, 27 of these were identified as persons infected with human immunodeficiency virus (HIV) and 4 persons identified at other places, were registered for followup. It was found that 51.3 percent of people were screened anonymously, reason for screening being epidemiological indications--history of blood transfusions, homosexual contacts, irregular sexual intercourse. The rest did not observe anonymity, 10.7 percent of these persons were screened by clinical indications. The in-depth clinical screening of patients who sought care in CDU, patients infected with HIV and persons who had contacts with them, required the consultative services of different specialists--dermatovenerologists, gynaecologists, sexologists, stomatologists and some others. It determined the necessity of establishing an outpatient department of "AIDS and AIDS-indicatory infections" which represented a new organizational form of AIDS service.     

Patient, physician, and payer perceptions and misperceptions of willingness to pay for diagnostic certainty

Little is known about the value patients, physicians, and payers place on intangible attributes of care. Differences in valuations among these groups and misperceptions of value of intangible attributes to other groups can contribute to conflicts about treatment recommendations or coverage decisions. We surveyed patients, physicians, and managed care executives to assess their willingness to pay (WTP) for diagnostic certainty for peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). To determine if patients, physicians, and payers accurately perceive each other's valuations of diagnostic certainty, participants were also asked to estimate the WTP of each of the other types of respondents. Patients were most likely, and executives least likely, to value diagnostic certainty. For PUD, 84% of patients, 61% of physicians, and 43% of executives expressed a positive WTP. Median WTP was low for all three groups ($1-9 for patients and physicians; $0 for payers). Physicians and executives both correctly predicted patient WTP. For GERD, 87% of patients, 52% of physicians, and 29% of executives expressed a positive WTP. Executives underestimated patient WTP. For both diseases, physicians' WTP was overestimated by patients and underestimated by executives. The inconsistency in the value that patients, physicians, and managed care executives place on diagnostic certainty indicates the potential for conflict over practice guidelines or access to services. WTP surveys can provide information to aid in anticipating and addressing areas of disagreement.     

Difficulties in moving routine medical checks from the specialist level to the general practitioner level

We began a project to move routine medical checks for appropriate patients from the specialist level to the patient's normal general practitioner (GP). The GP's analysis and conclusions would be checked by the specialist, using electronic messaging. The idea for the project came from the top level of the regional health authority. Despite that, the project was closed down before pilot testing began. We used stakeholder theory as a post-project evaluation to analyse what happened and where it went wrong. A common mistake in project planning is to focus the planning effort on system tasks and not to pay attention to a well-thought-out handling of the project's stakeholders. This was what happened in our project. Ideal objectives and good political intentions are not enough to implement a new e-health service.     

The effect of the full moon on general practice consultation rates

BACKGROUND: The effect of the full moon on human behaviour, the so-called 'Transylvania hypothesis', has fascinated the public and occupied the mind of researchers for centuries. OBJECTIVE: The aim of the present study was to determine whether or not there was any change in general practice consultation patterns around the time of the full moon. METHOD: We analysed data from the fourth national morbidity study of general practice. The data set was split into two groups and analysed separately: consultations on ordinary weekdays and consultations on weekends and bank holidays. The data were split randomly into two equal sets, one for model building and one for model validation. The lunar cycle effect was assumed to be sinusoidal, on the grounds that any effect would be maximal at the time of the full moon and decline to the new moon, following a cosine curve (with a period of 29.54 days, the mean length of a lunar cycle). RESULTS: There was a statistically significant, but small, effect associated with the lunar cycle of 1.8% of the mean value [95% confidence interval (CI) 0.9-2.7%]. This equates to an average difference between the two extremes during the cycle of 3.6%. For this data set, this accounts for 190 (95% CI 95-285) more consultations on days at the peak of the cycle compared with those at the bottom of the cycle, or, put another way, about three consultations per practice. CONCLUSION: We can speculate neither as to what the nature of these moon-related problems may be, nor as to the mechanisms underpinning such behaviour. However, we have confirmed that it does not seem to be related to anxiety and depression.     

Variability in rates of use of antibacterials among 130 US hospitals and risk-adjustment models for interhospital comparison.

OBJECTIVE: To describe variability in rates of antibacterial use in a large sample of US hospitals and to create risk-adjusted models for interhospital comparison. METHODS: We retrospectively surveyed the use of 87 antibacterial agents on the basis of electronic claims data from 130 medical-surgical hospitals in the United States for the period August 2002 to July 2003; these records represented 1,798,084 adult inpatients. Hospitals were assigned randomly to the derivation data set (65 hospitals) or the validation data set (65 hospitals). Multivariable models predicting rates of antibacterial use were created using the derivation data set. These models were then used to predict rates of antibacterial use in the validation data set, which was compared with observed rates of antibacterial use. Rates of antibacterial use was measured in days of therapy per 1,000 patient-days. RESULTS: Across the surveyed hospitals, a mean of 59.3% of patients received at least 1 dose of an antimicrobial agent during hospitalization (range for individual hospitals, 44.4%-73.6%). The mean total rate of antibacterial use was 789.8 days of therapy per 1,000 patient-days (range, 454.4-1,153.4). The best model for the total rate of antibacterial use explained 31% of the variance in rates of antibacterial use and included the number of hospital beds, the number of days in the intensive care unit per 1,000 patient-days, the number of surgeries per 1,000 discharges, and the number of cases of pneumonia, bacteremia, and urinary tract infection per 1,000 discharges. Five hospitals in the validation data set were identified as having outlier rates on the basis of observed antibacterial use greater than the upper bound of the 90% prediction interval for predicted antibacterial use in that hospital. CONCLUSION: Most adult inpatients receive antimicrobial agents during their hospitalization, but there is substantial variability between hospitals in the volume of antibacterials used. Risk-adjusted models can explain a significant proportion of this variation and allow for comparisons between hospitals for benchmarking purposes.