Shared care in the follow-up of early-stage melanoma: a qualitative study of Australian melanoma clinicians' perspectives and models of care

Background

Patients with early stage melanoma have high survival rates but require long-term follow-up to detect recurrences and/or new primary tumours. Shared care between melanoma specialists and general practitioners is an increasingly important approach to meeting the needs of a growing population of melanoma survivors.

Methods

In-depth qualitative study based on semi-structured interviews with 16 clinicians (surgical oncologists, dermatologists and melanoma unit GPs) who conduct post-treatment follow-up at two of Australia’s largest specialist referral melanoma treatment and diagnosis units. Interviews were recorded, transcribed and analysed to identify approaches to shared care in follow-up, variations in practice, and explanations of these.

Results

Melanoma unit clinicians utilised shared care in the follow-up of patients with early stage melanoma. Schedules were determined by patients’ clinical risk profiles. Final arrangements for delivery of those schedules (by whom and where) were influenced by additional psychosocial, professional and organizational considerations. Four models of shared care were described: (a) surgical oncologist alternating with dermatologist (in-house or local to patient); (b) melanoma unit dermatologist and other local doctor (e.g. family physician); (c) surgical oncologist and local doctor; or (d) melanoma physician and local doctor.

Conclusions

These models of shared care offer alternative solutions to managing the requirements for long-term follow-up of a growing number of patients with stage I/II melanoma, and warrant further comparative evaluation of outcomes in clinical trials, with detailed cost/benefit analyses.

Follow-up of early stage melanoma: specialist clinician perspectives on the functions of follow-up and implications for extending follow-up intervals

BACKGROUND

There is limited evidence on the relative effectiveness of different follow-up schedules for patients with AJCC stage I or II melanoma, but less frequent follow-up than is currently recommended has been proposed.

OBJECTIVES

To describe melanoma clinicians' perspectives on the functions of follow-up, factors that influence follow-up intervals, and important considerations for extending intervals.

METHODS

Qualitative interviews with 16 clinicians (surgical oncologists, dermatologists, melanoma unit physicians) who conduct follow-up at two of Australia's largest specialist centers.

RESULTS

Follow-up is conducted for early detection of recurrences or new primary melanomas, to manage patient anxiety, support patient self-care, and as part of shared care. Recommended intervals are based on guidelines but account for each patient's clinical risk profile, level of anxiety, patient education requirements, capacity to engage in skin self-examination, and how the clinician prefers to manage any suspicious lesions.

CONCLUSIONS

To revise guidelines and implement change it is important to understand the rationale underpinning existing practice. Extended follow-up intervals for early stage melanoma are more likely to be adopted after the first year when patients are less anxious and sufficiently prepared to conduct self-examination. Clinicians may retain existing schedules for highly anxious patients or those unable to examine themselves.

Patients who take their symptoms less seriously are more likely to have colorectal cancer

BACKGROUND

People vary in how they respond to symptoms. The purpose of this study was to assess whether serious disease is more likely to be present in patients who report that they take any symptoms less seriously than other people do, and to assess the reliability of a question which can be used to identify the extent to which patients take any symptom seriously. To do this we assessed whether the likelihood of detecting colorectal cancer is higher in patients who report that they take symptoms less seriously than other people do.

METHODS

Cross sectional study of 7736 patients who had colonoscopy to find colorectal cancer. Before colonoscopy, patients completed a questionnaire on bowel symptoms and were also asked: "Compared to other people of your age and sex, how seriously do you think you take any symptoms?" Likelihood of detecting colorectal cancer according to responses to this question was assessed by logistic regression models, unadjusted and adjusted for symptoms and other known predictors of colorectal cancer.Question reliability was assessed in a different sample using percentage agreement and the kappa statistic for the answers given by each patient on two occasions. Agreement between patient and doctor responses was also assessed (n = 108).

RESULTS

Patients who reported they took symptoms less seriously were 3.28 (95%CI: 2.02, 5.33) times more likely to have colorectal cancer than patients who took symptoms more seriously than others. The effect was smaller (1.85 (95%CI: 1.11, 3.09)), but remained statistically significant in models including symptoms and other predictors of colorectal cancer. The question was reliable: on repeat questioning, 70% of responses were in absolute agreement and 92% were within 1 category, kappa 57%. Patient-doctor agreement was 66%, within 1 category 92%, kappa 48%.

CONCLUSION

Patients who take their symptoms less seriously have a considerably higher likelihood of colorectal cancer than those who identify themselves as taking any symptoms more seriously than other people. The question is easy to ask and has good reliability. Doctors also reliably identify how patients assess themselves. Assessment of how seriously patients take any symptoms can contribute to the clinical assessment of a patient.

Psychosocial aspects of post-treatment follow-up for stage I/II melanoma: a systematic review of the literature

BACKGROUND

Patients treated for melanoma are advised to have lifelong full body skin examinations. Extended intervals between examinations have been proposed, but although this may be clinically effective, psychosocial aspects of follow-up are not well understood. This systematic review summarised patient and clinician preferences, experiences and adherence with recommended follow-up of stage I/II melanoma.

METHODS

Medline, PsycINFO, CINAHL, Embase, Cochrane Library, ACP Journal Club and NHS Economic Evaluation Database were searched from database inception to week 3 April 2010, to identify original studies of psychosocial outcomes of follow-up after treatment of stage I/II primary cutaneous melanoma, as reported by patients or clinicians. The results were synthesised, and characteristics likely to maximise patients' well-being and adherence to follow-up schedules were proposed.

RESULTS

We found 15 studies that met the inclusion criteria. Anxiety with melanoma follow-up was common; patients valued reassurance, information and psychosocial support, but long-term adherence to schedules was variable. Some wanted more emotional support from their clinician than was provided. Clinicians sometimes ordered additional blood and imaging tests to reassure patients. GPs were hesitant to conduct melanoma follow-up, but a trial providing technical training and protocols reported positive outcomes. Both patients and GPs wanted prompt access to melanoma specialists when suspicious lesions were found.

CONCLUSION

Psychosocial aspects of follow-up impact on patient well-being and potential adherence to schedules, and may influence clinician practice. If follow-up schedules or personnel are to be revised, psychosocial impacts on patients must be explicitly addressed, as well as guidance and specialist support for clinicians.

Optimal allocation of participants for the estimation of selection, preference and treatment effects in the two-stage randomised trial design

Outcomes in clinical trials may be affected by the choice of treatment that participants might make, if they were indeed allowed to choose (a so-called selection effect), and by whether they actually receive their preferred treatment (a preference effect). Selection and preference effects can be important, but they cannot be estimated in the conventional trial design. An alternative approach is the two-stage randomised trial, in which participants are first randomly divided into two subgroups. In one subgroup, participants are randomly assigned to treatments, while in the other, participants are allowed to choose their own treatment. This approach yields estimates of the direct treatment effect, and of the preference and selection effects. The latter two provide insight that goes considerably beyond what is possible in the standard randomised trial. In this paper, we determine the optimal proportion of participants who should be allocated to the choice subgroup. The precision of the estimated selection, preference and treatment effects are functions of: the total sample size; the proportion of participants allocated to choose their treatment; the variances of the outcome; the proportions of participants who select each treatment in the choice group; and the selection, preference and treatment effects themselves. We develop general expressions for the optimum proportion of participants in the choice group, depending on which effects are of primary interest. We illustrate the results with trial data comparing alternative clinical management strategies for women with abnormal results on cervical screening.

Effect of dependent errors in the assessment of diagnostic or screening test accuracy when the reference standard is imperfect

When no gold standard is available to evaluate a diagnostic or screening test, as is often the case, an imperfect reference standard test must be used instead. Furthermore, the errors of the test and its reference standard may not be independent. Some authors have opined that positively dependent errors will lead to overestimation of test performance. Although positive dependence does increase agreement between the test and the reference standard, it is not clear if test accuracy will necessarily be overestimated in this situation, and the case of negatively associated test errors is even less clear. To examine this issue in more detail, we derive the apparent sensitivity, specificity, and overall accuracy of a test relative to an imperfect reference standard and the bias in these parameters. We demonstrate that either positive or negative bias can occur if the reference standard is imperfect. The type and magnitude of bias depend on several components: the disease prevalence, the true test sensitivity and specificity, the covariance between the false-negative test errors among the true disease cases, and the covariance between the false-positive test errors among the true noncases. If, for example, sensitivity and specificity are 0.8 for both the test and reference standard and the errors have a moderate positive dependence, test sensitivity is then underestimated at low prevalence but overestimated at high prevalence, while the opposite occurs for specificity. We illustrate these ideas through general numerical calculations and an empirical example of screening for breast cancer with magnetic resonance imaging and mammography.

The potential value of monitoring bone turnover markers among women on alendronate

Biochemical markers of bone turnover have been proposed to monitor the response to bisphosphonate therapy for osteoporosis, but this requires true between-person differences in the response to therapy. Using mixed models we analyzed three annual measurements of two markers (bone alkaline phosphatase [BAP] and cross-linked N-telopeptide of type I collagen [NTX]) from the Fracture Intervention Trial. We compared marker variation among women allocated to alendronate with that among women allocated to placebo to estimate how much variation was due to true between-person differences in response to treatment, and how much was due to random within-person fluctuations unrelated to treatment. For both markers we found that the mean effect of treatment differed by the baseline level of the marker. After allowing for this and other effects, we found large true between-person differences in response to treatment for both markers, with a coefficient of variation (CV) for NTX of 25.1% and for BAP of 21.2%. However, random within-person fluctuation was even larger, with a CV for change in NTX of 42.5% and for change in BAP of 25.8%. Although repeated measurements have the potential to reduce within person variability, even triplicate baseline marker measurements resulted in an averaged value that was only within 31% of the true value with 95% certainty. In summary, although bone turnover markers appear promising for monitoring between-person differences in response to treatment, their use in clinical practice is currently limited by large random within-person variation.

Optimizing the Frequency of Follow-Up Visits for Patients Treated for Localized Primary Cutaneous Melanoma

Purpose

To develop more evidence-based guidelines for the frequency of patient follow-up after treatment of localized (American Joint Committee on Cancer [AJCC] stage I or II) melanoma.

Methods

We used data from Melanoma Institute Australia on an inception cohort of 3,081 consecutive patients first diagnosed with stage I or II melanoma between January 1985 and December 2009. Kaplan-Meier curves and Cox models were used to characterize the time course and predictors for recurrence and new primaries. We modeled the delay in diagnosis of recurrence or new primary as well as the number of monitoring visits required using two monitoring schedules: first, according to 2008 Australian and New Zealand guidelines and, second, with fewer visits, especially for those at lowest risk of recurrence.

Results

For every 1,000 patients beginning follow-up, 229 developed recurrence and 61 developed new primary within 10 years. There was only a small difference in modeled delay in diagnosis (extra 44.9 and 9.6 patients per 1,000 for recurrence and new primary, respectively, with delay greater than 2 months) using a schedule that requires far fewer visits (3,000 fewer visits per 1,000 patients) than recommended by current guidelines. AJCC substage was the most important predictor of recurrence, whereas age and date of primary diagnosis were important predictors of developing new primary.

Conclusion

By providing less intensive monitoring, more efficient follow-up strategies are possible. Fewer visits with a more focused approach may address the needs of patients and clinicians to detect recurrent or new melanoma.

Effects of additional blood pressure and lipid measurements on the prediction of cardiovascular risk

BACKGROUND

Current guidelines recommend that decisions to start preventative therapy for cardiovascular disease (CVD) should be based on absolute risk; however, current risk equations are based on single measurements of risk factors. We aimed to assess whether two measurements of blood pressure and lipids improves the prediction of cardiovascular risk compared to one measurement.

METHODS AND RESULTS

We used sex-specific Cox proportional hazards models to evaluate the risk of first CVD event in 2385 participants of the Framingham Offspring Study attending both the second and third visits. We estimated the effects on risk prediction of using the average of two measurements of blood pressure, total cholesterol, and HDL cholesterol compared to using one measurement of the risk factors. We found that these risk factors were each markedly more predictive of CVD when the average of two measurements was used rather than one measurement and age was less predictive of CVD. There were small improvements in the overall model fit, discrimination, and calibration. Reclassification also showed small improvements across the risk spectrum (net reclassification information, NRI, for women 3.0%, 95% CI -0.9 to 24.8%; NRI for men 4.0%, 95% CI -2.2 to 14.1%) and possibly greater improvements for intermediate-risk individuals (NRI for women 32.3%, 95% CI -21.9 to 46.8%; NRI for men 16.0%, 95% CI -3.3 to 43%).

CONCLUSIONS

Averaging two measurements of blood pressure and lipids results in marked increases in the predictiveness of these risk factors and smaller improvements in the overall prediction of cardiovascular risk including reclassification.

The value of age and medical history for predicting colorectal cancer and adenomas in people referred for colonoscopy

BACKGROUND

Colonoscopy is an invasive and costly procedure with a risk of serious complications. It would therefore be useful to prioritise colonoscopies by identifying people at higher risk of either cancer or premalignant adenomas. The aim of this study is to assess a model that identifies people with colorectal cancer, advanced, large and small adenomas.

METHODS

Patients seen by gastroenterologists and colorectal surgeons between April 2004 and December 2006 completed a validated, structured self-administered questionnaire prior to colonoscopy. Information was collected on symptoms, demographics and medical history. Multinomial logistic regression was used to simultaneously assess factors associated with findings on colonoscopy of cancer, advanced adenomas and adenomas sized 6 -9 mm, and ≤ 5 mm. The area under the curve of ROC curve was used to assess the incremental gain of adding demographic variables, medical history and symptoms (in that order) to a base model that included only age.

RESULTS

Sociodemographic variables, medical history and symptoms (from 8,204 patients) jointly provide good discrimination between colorectal cancer and no abnormality (AUC 0.83), but discriminate less well between adenomas and no abnormality (AUC advanced adenoma 0.70; other adenomas 0.67). Age is the dominant risk factor for cancer and adenomas of all sizes. Having a colonoscopy within the last 10 years confers protection for cancers and advanced adenomas.

CONCLUSIONS

Our models provide guidance about which factors can assist in identifying people at higher risk of disease using easily elicited information. This would allow colonoscopy to be prioritised for those for whom it would be of most benefit.

How do we achieve informed choice for women considering breast screening?

OBJECTIVE

In current medical literature, mammography and other cancer screening programs are subject to controversy because of debate about the magnitude and nature of the benefits and harms. This paper discusses the issues around informed choice for women considering breast screening.

METHOD

We discuss qualitative and quantitative studies of women's attitudes to breast screening and informed choice.

RESULTS

Women view breast screening as a way of avoiding potential regret, and reassurance from normal results is highly valued. Screening participants acknowledge anxiety about false positives but awareness regarding potential overdetection of indolent breast cancer is minimal, and research is needed to assess how better understanding of screening downsides may affect women's views. In any case, weighing up screening advantages and disadvantages is sensitive to personal preferences.

CONCLUSIONS

Communicators have an ethical obligation to make balanced information available to women, which is flexible enough to respond to the level of detail and involvement desired by each individual. Many women want to know more and to participate more actively in screening decisions. Techniques have been developed to present balanced information and support individual decision making in ways that are accessible and empowering for the wider community. Evaluations of breast cancer screening must integrate clinical data with evidence on the perspectives of women themselves.

Control charts demonstrated limited utility for the monitoring of lung function in asthma

OBJECTIVE

Statistical process control charts have been advocated for use in monitoring of lung function in asthma. We aimed to evaluate their application in asthma using existing data from a randomized trial.

STUDY DESIGN AND SETTING

Patients on optimal inhaled corticosteroid/bronchodilator therapy (n=81) were randomized to continue the same or change to corticosteroid alone. Baseline statistical control was assessed from 20 days of electronically recorded lung function (peak expiratory flow [PEF], forced expiratory volume in one second [FEV(1)]). The ability to detect lung function changes was assessed during 10 days after randomization.

RESULTS

PEF measurements were in statistical control during baseline for only 59-79% of patients for different combinations of five control chart rules (e.g., Rule 1: >3 standard deviations outside mean and 95% expected to be in control), with similar proportions for FEV(1). After randomization, among those previously in statistical control, Rule 1 signaled lower FEV(1) for 35% of patients randomized to treatment change compared with 6% continuing baseline treatment (P=0.004). Control charts performed poorly for PEF, signaling a decrease for 8% of patients randomized to treatment change compared with 11% continuing treatment (P=0.7). A paradoxical increase was signaled for many patients continuing treatment.

CONCLUSION

Control charts may not be suitable for use in many patients with asthma.

Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a systematic review

BACKGROUND

Bowel symptoms are often considered an indication to perform colonoscopy to identify or rule out colorectal cancer or precancerous polyps. Investigation of bowel symptoms for this purpose is recommended by numerous clinical guidelines. However, the evidence for this practice is unclear. The objective of this study is to systematically review the evidence about the association between bowel symptoms and colorectal cancer or polyps.

METHODS

We searched the literature extensively up to December 2008, using MEDLINE and EMBASE and following references. For inclusion in the review, papers from cross sectional, case control and cohort studies had to provide a 2×2 table of symptoms by diagnosis (colorectal cancer or polyps) or sufficient data from which that table could be constructed. The search procedure, quality appraisal, and data extraction was done twice, with disagreements resolved with another reviewer. Summary ROC analysis was used to assess the diagnostic performance of symptoms to detect colorectal cancer and polyps.

RESULTS

Colorectal cancer was associated with rectal bleeding (AUC 0.66; LR+ 1.9; LR- 0.7) and weight loss (AUC 0.67, LR+ 2.5, LR- 0.9). Neither of these symptoms was associated with the presence of polyps. There was no significant association of colorectal cancer or polyps with change in bowel habit, constipation, diarrhoea or abdominal pain. Neither the clinical setting (primary or specialist care) nor study type was associated with accuracy.Most studies had methodological flaws. There was no consistency in the way symptoms were elicited or interpreted in the studies.

CONCLUSIONS

Current evidence suggests that the common practice of performing colonoscopies to identify cancers in people with bowel symptoms is warranted only for rectal bleeding and the general symptom of weight loss. Bodies preparing guidelines for clinicians and consumers to improve early detection of colorectal cancer need to take into account the limited value of symptoms.

Meta-analysis of the impact of surgical margins on local recurrence in women with early-stage invasive breast cancer treated with breast-conserving therapy

PURPOSE

There is no consensus on what constitutes adequate negative margins in breast-conserving therapy (BCT). We review the evidence on surgical margins in BCT for early-stage invasive breast cancer.

METHODS

Meta-analysis of studies reporting local recurrence (LR) relative to quantified final microscopic margin status and the threshold distance for negative margins. The proportion of LR was modelled using random effects logistic meta-regression.

RESULTS

Based on 21 studies (LR in 1,026 of 14,571 subjects) the odds of LR were associated with margin status [model 1: odds ratio (OR) = 2.02 for positive/close versus negative; model 2: OR = 1.80 for close versus negative, 2.42 for positive versus negative (P<0.001 both models)] but not with margin distance [1mm versus 2mm versus 5mm (P > 0.10 both models)], adjusting for median follow-up time. However, there was weak evidence in both models that the odds of LR decreased as the threshold distance for declaring negative margins increased. This bordered significance in model 2 [OR for 1mm, 2mm, 5mm: 1.0, 0.75, 0.51 (P = 0.097 for trend)], and was not significant in model 1 [OR for 1mm, 2mm, 5mm: 1.0, 0.85, 0.58 (P = 0.11 for trend)] but was evident when one study (of women ≤ 40 years) was excluded from this model [OR for 1mm, 2mm, 5mm: 1.0, 0.72, 0.52 (P = 0.058 for trend)]: this trend was rendered insignificant by adjustment for the proportion of subjects receiving a radiation boost or the proportion of subjects receiving endocrine therapy.

CONCLUSIONS

Margin status has a prognostic effect in all women treated for invasive breast cancer; increasing the threshold distance for declaring negative margins is weakly associated with reduced odds of LR, however adjustment for covariates (adjuvant therapy) removes the significance of this effect. Adoption of wider margins, relative to narrower widths, for declaring negative margins is unlikely to a have substantial additional benefit for long-term local control in BCT.

Accuracy and outcomes of screening mammography in women with a personal history of early-stage breast cancer

CONTEXT

Women with a personal history of breast cancer (PHBC) are at risk of developing another breast cancer and are recommended for screening mammography. Few high-quality data exist on screening performance in PHBC women.

OBJECTIVE

To examine the accuracy and outcomes of mammography screening in PHBC women relative to screening of similar women without PHBC.

DESIGN AND SETTING

Cohort of PHBC women, mammogram matched to non-PHBC women, screened through facilities (1996-2007) affiliated with the Breast Cancer Surveillance Consortium.

PARTICIPANTS

There were 58,870 screening mammograms in 19,078 women with a history of early-stage (in situ or stage I-II invasive) breast cancer and 58,870 matched (breast density, age group, mammography year, and registry) screening mammograms in 55,315 non-PHBC women.

MAIN OUTCOME MEASURES

Mammography accuracy based on final assessment, cancer detection rate, interval cancer rate, and stage at diagnosis.

RESULTS

Within 1 year after screening, 655 cancers were observed in PHBC women (499 invasive, 156 in situ) and 342 cancers (285 invasive, 57 in situ) in non-PHBC women. Screening accuracy and outcomes in PHBC relative to non-PHBC women were cancer rates of 10.5 per 1000 screens (95% CI, 9.7-11.3) vs 5.8 per 1000 screens (95% CI, 5.2-6.4), cancer detection rate of 6.8 per 1000 screens (95% CI, 6.2-7.5) vs 4.4 per 1000 screens (95% CI, 3.9-5.0), interval cancer rate of 3.6 per 1000 screens (95% CI, 3.2-4.1) vs 1.4 per 1000 screens (95% CI, 1.1-1.7), sensitivity 65.4% (95% CI, 61.5%-69.0%) vs 76.5% (95% CI, 71.7%-80.7%), specificity 98.3% (95% CI, 98.2%-98.4%) vs 99.0% (95% CI, 98.9%-99.1%), abnormal mammogram results in 2.3% (95% CI, 2.2%-2.5%) vs 1.4% (95% CI, 1.3%-1.5%) (all comparisons P < .001). Screening sensitivity in PHBC women was higher for detection of in situ cancer (78.7%; 95% CI, 71.4%-84.5%) than invasive cancer (61.1%; 95% CI, 56.6%-65.4%), P < .001; lower in the initial 5 years (60.2%; 95% CI, 54.7%-65.5%) than after 5 years from first cancer (70.8%; 95% CI, 65.4%-75.6%), P = .006; and was similar for detection of ipsilateral cancer (66.3%; 95% CI, 60.3%-71.8%) and contralateral cancer (66.1%; 95% CI, 60.9%-70.9%), P = .96. Screen-detected and interval cancers in women with and without PHBC were predominantly early stage.

CONCLUSION

Mammography screening in PHBC women detects early-stage second breast cancers but has lower sensitivity and higher interval cancer rate, despite more evaluation and higher underlying cancer rate, relative to that in non-PHBC women.

Monitoring adherence to drug treatment by using change in cholesterol concentration: secondary analysis of trial data

OBJECTIVE

To estimate the accuracy of monitoring cholesterol concentration for detecting non-adherence to lipid lowering treatment.

DESIGN

Secondary analysis of data on cholesterol concentration in the LIPID (long term intervention with pravastatin in ischaemic disease) study by using three measures of non-adherence: discontinuation of treatment, allocation to placebo arm, less than 80% of pills taken.

SETTING

Randomised placebo controlled trial in Australia and New Zealand.

PARTICIPANTS

9014 patients with previous coronary heart disease.

INTERVENTIONS

Pravastatin 40 mg or placebo daily.

MAIN OUTCOME MEASURES

Sensitivity, specificity, area under the receiver operating characteristics (ROC) curve, post-test probability.

RESULTS

Monitoring of cholesterol concentration had modest ability for detecting complete non-adherence. One year after the start of treatment, half (1957/3937) of the non-adherent patients and 6% (253/3944) of adherent patients had a rise in concentration of low density lipoprotein cholesterol. Accuracy was reasonable (area under the curve 0.89). Cholesterol monitoring, however, had weak ability for detecting partial non-adherence. One year after the start of treatment, 16% (34/213) of partially adherent and 4% (155/3585) of fully adherent patients had a rise in concentration of low density lipoprotein cholesterol. Accuracy was poor (area under the curve 0.65). For typical pre-test probabilities of non-adherence ranging from low (25%) to high (75%), the post-test probabilities indicate continuing uncertainty after lipid testing. A patient with no change in low density lipoprotein cholesterol concentration has a post-test probability of being completely non-adherent of between 67% and 95% and a post-test probability of being partially non-adherent of between 48% and 89%. A patient with a decrease in concentration of 1.0 mmol/L has a post-test probability of being completely non-adherent of between 7% and 40% and a post-test probability of being partially non-adherent of between 21% and 71%.

CONCLUSIONS

Monitoring concentration of low density lipoprotein (or total) cholesterol has modest ability to detect complete non-adherence or non-persistence with pravastatin treatment and weak ability to detect partial non-adherence. Results of monitoring should be considered as no more than an adjunct to careful discussion with patients about adherence.

When should one adjust for measurement error in baseline variables in observational studies?

Previously, we showed that in randomised experiments, correction for measurement error in a baseline variable induces bias in the estimated treatment effect, and conversely that ignoring measurement error avoids bias. In observational studies, non-zero baseline covariate differences between treatment groups may be anticipated. Using a graphical approach, we argue intuitively that if baseline differences are large, failing to correct for measurement error leads to a biased estimate of the treatment effect. In contrast, correction eliminates bias if the true and observed baseline differences are equal. If this equality is not satisfied, the corrected estimator is also biased, but typically less so than the uncorrected estimator. Contrasting these findings, we conclude that there must be a threshold for the true baseline difference, above which correction is worthwhile. We derive expressions for the bias of the corrected and uncorrected estimators, as functions of the correlation of the baseline variable with the study outcome, its reliability, the true baseline difference, and the sample sizes. Comparison of these expressions defines a theoretical decision threshold about whether to correct for measurement error. The results show that correction is usually preferred in large studies, and also in small studies with moderate baseline differences. If the group sample sizes are very disparate, correction is less advantageous. If the equivalent balanced sample size is less than about 25 per group, one should correct for measurement error if the true baseline difference is expected to exceed 0.2-0.3 standard deviation units. These results are illustrated with data from a cohort study of atherosclerosis.

Determining the Impact of Informed Choice

Background. The Rucker 2-stage randomized trial (RCT) design and method allows treatment, preference, and selection effects to be estimated separately in clinical trials. Objective. To understand the effect of patient choice on patient outcomes, the authors applied the Rucker design and analysis method. Design. They used data from a trial of management strategies for women with atypical cells of undetermined significance (ASCUS) detected at routine cervical screening, in which informed choice using a decision aid was compared to no choice. Setting. Women’s health clinics across Australia. Patients. Women aged 18 to 70 years (n = 314) with ASCUS. Intervention. Women were randomized to either an informed choice of human papillomavirus (HPV) triage testing or repeat Pap testing or to no choice with random allocation to management by either option. Measurements. Health-related quality of life (SF36) and satisfaction were measured over the course of management and up to 1 year after triage. Results. Using the Rucker analysis, patients who received their choice had higher quality of life scores than those who did not choose (SF36 MCS, 6% higher, 6.0; 95% confidence interval: −0.6 to 12.9; P = 0.07; effect size 0.61 [moderate]). In contrast, the traditional RCT analysis suggested there was little difference in quality of life between the choice and no-choice trial arms. Limitations. The Rucker method assumes that the declared preferences for treatment in the choice arm are representative of the preferences that would have been observed in the no-choice arms if choice was available. Conclusions. The Rucker method should be used to estimate treatment, preference, and selection effects in randomized trials, as it adds to our understanding of the effect of choice on patient outcomes.

Monitoring Adherence to Medication by Measuring Change in Blood Pressure

After starting antihypertensives, blood pressure is monitored for several reasons, including assessment of adherence. We aimed to estimate the accuracy of blood pressure monitoring for detecting early nonadherence. We conducted a secondary analysis of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), a large randomized trial of blood pressure lowering to reduce the risk of recurrent stroke. We compared change in blood pressure 3 months after randomization in people who had discontinued treatment (nonadherent) with those who stayed on treatment (adherent). We also used an indirect method, assessing whether change in blood pressure discriminated between active (adherent) and placebo (nonadherent) groups. Both methods gave similar results. For the 3433 subjects, the mean (SD) of the change in systolic blood pressure was −15.8 mm Hg (SD 18.7 mm Hg) in the adherent group and −4.2 mm Hg (SD 18.1 mm Hg) in the nonadherent group. After recalibration of the mean change in the nonadherent group to 0 mm Hg and in the adherent group to −11.6 mm Hg, the absence of a fall in systolic blood pressure at 3 months had a sensitivity of 50% and a specificity of 80% for detecting nonadherence (50% of nonadherent patients and 20% of adherent patients had a rise in blood pressure). Discriminatory power was modest over the range of cutoffs (area under the receiver–operator curve 0.67). Monitoring blood pressure is poor at detecting nonadherence to blood pressure–lowering treatment. Further research should look at other methods of assessing adherence.