***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Abstract Purpose : To examine the performance of an instrument to assess adherence based on a visual analogue scale , compared to an instrument based on 3-day recall , using unannounced pill counts in the place of residence as the gold st and ard . Method : We prospect ively assessed adherence to antiretroviral therapy in 84 marginally housed indigent HIV-infected patients who were receiving stable antiretroviral therapy in San Francisco , California , with three adherence assessment s over no more than 4 months . Results : Mean adherence using the  visual analogue scale , 3-day recall , and unannounced pill count methods were 82.5 % , 84.2 % , and 75.9 % , respectively . The correlation between visual analogue scale and unannounced pill count was high ( r = 0.76 ) and was not statistically different from that between 3-day recall and unannounced pill count ( r = 0.71 ; p = .52 ) . Both methods were also similarly inversely correlated with HIV viral load ( r = -0.49 and -0.34 , respectively ; p = .22 for the difference in the correlations ) . The visual analogue scale correlation with unannounced pill count was stable over time and remained high in all sub population s examined . Conclusion : A visual analogue scale to assess adherence was performed as well as a more complicated 3-day recall instrument in this diverse population . Given its simplicity , the visual analogue scale adherence instrument will be useful in research and may be useful in routine patient care High blood pressure ( HBP ) is one of the most important risk factors for morbidity and mortality in the world . Non-adherence to medication is associated with the lack of control of HBP . The objective of this study was to assess the validity of four indirect methods for measuring adherence to medication to control HBP in primary health care . A r and om sample of 120 hypertensive patients who were undergoing treatment for at least 2 months in a primary care unit in Florianópolis ( Brazil ) were included in the study . The independent variables were four indirect methods to measure adherence to medication : knowledge regarding the HBP medication , the blood pressure level , attitude regarding the medication intake ( Morisky – Green test ) and self-reported adherence .  The classification of HBP was based on criteria established by the Brazilian Ministry of Health . The gold st and ard used for measuring adherence was the pill count . Logistic regression was used to estimate sensitivity ( highest value of 88.2 % for self-report ) , specificity ( highest value of 70.7 % for HBP control ) , positive predictive value ( highest value of 46.4 % for HBP control ) and negative predictive value ( highest value of 79.1 % for Morisky – Green test ) for each of the indirect methods . No indirect method of measuring adherence had a good positive predictive value for adherence , which was best predicted by patients ' age and whether they managed to control HBP . The results also revealed low treatment adherence ( 31.2 % ) and low control of HBP ( 37.6 % ) . Non-adherence was mainly associated with side effects of the treatment AIDS Clinical Trials Group ( ACTG ) 359 was a r and omized , partially double-blinded factorial study of 6 antiretroviral regimens , all including saquinavir , among HIV-infected persons in whom prior therapy had failed ( n = 258 ) . Counts of remaining saquinavir capsules were determined between weeks 0 and 4 ; at weeks 4 , 8 , and 16 , self-reported adherence was estimated from 2-day report of doses skipped , therapeutic coverage , and percent of doses taken were determined by electronic monitoring devices applied to saquinavir bottles , and the saquinavir 24-hour area under the curve ( AUC ) was estimated . Relationships were evaluated among these 4 adherence measures and the primary endpoint of week 16 HIV RNA change . Thirty percent of 254 subjects had HIV RNA ≤500 copies/mL at week 16 . Only self-reported adherence and saquinavir AUC were significantly associated with week 16 HIV RNA change ( P = 0.019 and 0.023 , respectively ) , and these measures were higher in subjects with week 16 HIV RNA ≤500 copies/mL ( P = 0.03 and 0.008 , respectively ) . The ability to detect a correlation between electronically monitored adherence and virologic response was limited by the small sample size . Self-reported adherence and saquinavir AUC were significant predictors of virologic response , in this evaluation . These findings provide insight into methods of assessing and improving adherence to antiretroviral regimens BACKGROUND Nonadherence to physician treatment recommendations is an increasingly recognized cause of adverse outcomes and increased health care costs , particularly among patients with cardiovascular disease . Whether patient self-report can provide an accurate assessment of medication adherence in out patients with stable coronary heart disease is unknown . METHODS We prospect ively evaluated the risk of cardiovascular events associated with self-reported medication nonadherence in 1015 out patients with established coronary heart disease from the Heart and Soul Study . We asked participants a single question : " In the past month , how often did you take your medications as the doctor prescribed ? " Nonadherence was defined as taking medications as prescribed 75 % of the time or less . Cardiovascular events ( coronary heart disease death , myocardial infa rct ion , or stroke ) were identified by review of medical records during 3.9 years of follow-up . We used Cox proportional hazards analysis to determine the risk of adverse cardiovascular events associated with self-reported medication nonadherence . RESULTS Of the 1015 participants , 83 ( 8.2 % ) reported nonadherence to their medications , and 146 ( 14.4 % ) developed cardiovascular events . Nonadherent participants were more likely than adherent participants to develop cardiovascular events during 3.9 years of follow-up ( 22.9 % vs 13.8 % , P = .03 ) . Self-reported nonadherence remained independently predictive of adverse cardiovascular events after adjusting for baseline cardiac disease severity , traditional risk factors , and depressive symptoms ( hazards ratio , 2.3 ; 95 % confidence interval , 1.3 - 4.3 ; P = .006 ) . CONCLUSIONS In out patients with stable coronary heart disease , self-reported medication nonadherence is associated with a greater than 2-fold increased rate of subsequent cardiovascular events . A single question about medication adherence may be a simple and effective method to identify patients at higher risk for adverse cardiovascular events The relationship between adherence to highly active antiretroviral therapy ( HAART ) and RNA-HIV viral load outcomes has been extensively shown . Although there are different procedures for assessing treatment adherence , there is no ideal method . We present the SERAD ( Self-Reported Adherence ) question naire , a qualitative and quantitative self-reported instrument design ed to provide an easier adherence measurement . We also compared the question naire to three other methods to evaluate adherence to HAART regimens in HIV-infected patients . Two prospect i ve , observational , longitudinal studies were developed : a single-center pilot study followed by a multicenter study . A total of 530 HIV-infected out patients was prospect ively included , 66 in the pilot study and 464 in the multicenter study . Four methods were used to study adherence to HAART regimens : the SERAD question naire , pill count , electronic monitoring , and  plasma drug monitoring . Pearson 's correlations and Bl and and Altman 's method were developed . The SERAD question naire showed good feasibility and significant validity . Adequate levels of agreement between methods were observed , particularly when adherence was high . Differences increased as adherence fell . Moreover , the question naire was completed correctly , the interviewers did not report uncovered aspects , and the information was collected easily . Our results suggest that the SERAD question naire is a feasible and useful instrument for assessing adherence to HAART regimens in HIV-infected patients , and makes it possible to obtain reliable qualitative and quantitative information related to treatment adherence A step-wise approach to identify valid and feasible methods to detect non-adherence to tuberculosis drugs was evaluated in a prospect i ve study among pulmonary tuberculosis patients in an outpatient clinic in Indonesia . First , adherence was measured by  self-reporting with the st and ardized Morisky question naire , physician assessment , pill-count , visit attendance , diary and an electronic medication event monitoring system ( MEMS ) .  Next , validity of single methods was assessed against MEMS as gold st and ard . Feasibility of methods was then judged by physicians in the field . Finally , when valid and feasible methods were combined , it appeared that self-reporting by a question naire plus physician assessment could identify all non-adherent patients . It is recommended to use a systematic approach to develop a valid and locally feasible combination of methods to detect non-adherence to TB drugs Nonadherence to immunosuppressants in renal transplant recipients is a major factor affecting graft survival , but it is difficult to detect accurately in clinical practice . Adherence was measured in 153 adult renal transplant recipients using self-report question naires and interview , clinician rating , and cyclosporine levels . The sensitivity and specificity of these measures were determined by comparison with electronic monitoring in a r and omly selected sub sample of 58 subjects . Measures of adherence in current clinical use do not perform well when tested against electronic monitoring .  Self-report at a confidential interview was the best measure of adherence for the detection of both missed doses and erratic timing of medication . However , the use of a confidential interview is not directly applicable to a clinical setting . Further research on how best to facilitate disclosure in clinical setting s may be the best way to develop adherence measures for use in routine practice A two-group r and omized experimental design was employed to assess the effects of monitoring and feedback on the compliance of 93 psychiatric out patients treated with lithium . Compliance in both groups was measured using self-report , lithium level , appointment-keeping , and medication refill frequency . The experimental group was also monitored using a unique electronic device that records the time and day pills are removed . At the midpoint of the study , the experimental group received feedback about serum lithium levels and patterns of removing medications from the monitoring device while the control group received feedback about serum lithium levels only . The study demonstrated no sustained effect of the monitoring and feedback interventions on compliance Improved therapeutic strategies , including the introduction of protease inhibitors , have led to a striking decrease in HIV-related morbidity and mortality ( 1 , 2 ) . It is widely believed that adherence to an antiretroviral regimen is central to the likelihood that a patient will derive sustained benefit from therapy ( 3 , 4 ) . Conventional wisdom holds that two groups of patients are currently experiencing clinical and virologic failure . The first group consists of patients who have received multiple different antiretroviral drugs over a prolonged period of time and who may be infected predominantly with HIV strains that are resistant to multiple drugs . The second group comprises patients who adhere poorly to their antiretroviral regimen .  The two groups are not mutually exclusive : Patients with suboptimal adherence may be more likely to have antiretroviral drugresistant HIV infection . The potential public health importance of adherence to therapy in prevention of transmission of drug-resistant virus has also been emphasized ( 5 ) . Patients with suboptimal adherence to antiretroviral therapy and poor adherence to use of safer-sex practice s , such as use of condoms , may infect others with their own antiretroviral drugresistant virus . Anecdotal experience suggests that physicians may be unwilling to prescribe combination antiretroviral therapy to patients whom they perceive to be at high risk for poor adherence ( 6 ) . Given the critical importance of adherence to therapy to patient outcome , secondary prevention of HIV infection , and willingness of providers to prescribe therapy , we prospect ively investigated the association between protease inhibitor adherence and patient outcome , factors related to adherence , and the accuracy of physicians ' prediction of patient adherence . We used a microelectronic monitoring system to assess adherence to antiretroviral therapy . Methods Study Sample The study was conducted at the HIV clinics of the Veterans Affairs Medical Center , Pittsburgh , Pennsylvania , and University of Nebraska Medical Center , Omaha , Nebraska . The HIV physicians at these clinics were primary care providers for the study patients . Each site also had a dedicated HIV nurse coordinator . From August 1997 to March 1999 , we enrolled consecutive patients with HIV infection who were already receiving a protease inhibitor ( experienced patients ) or who were to begin taking a protease inhibitor ( naive patients ) . Exclusion criteria were inability to give informed written consent ; expectation of continued use of a medication organizer to include protease inhibitors ; and residence in a nursing home , jail , or hospice , where medications were dispensed at least daily . Collection of Baseline Data At baseline , a study investigator used medical chart review to complete a 52-item question naire for each patient . The question naire covered demographic information ( age , sex , ethnicity , risk factors for HIV infection , educational and employment status , income ) , medical history ( years known to be HIV infected ; opportunistic infections ; history of schizophrenia , depression , or bipolar affective disorder ) , and medication use ( name , dose , and frequency of all antiretroviral agents , other antimicrobials , and other prescription therapies ) . The enrolling physician assessed use of illegal drugs and nonprescription therapies ( including herbal or alternative therapies ) by interview . Alcohol abuse was assessed by using 
    Output:
    
Few were design ed to have the ability to be completed by or in conjunction with carers and few were able to distinguish between different types of non-adherence , which limited their ability be used effectively in the continuous improvement of targeted adherence enhancing interventions .
The data available suggested that patients find it easier to estimate general adherence than to report a specific number of doses missed .
Visual analogue scales can be easier for patients than other types of scale but are not suitable for telephone administration .