One of the more important developments in health care in the past decade may be the recognition that the patient's perspective is as legitimate and valid as the clinician's in monitoring health care outcomes 12. The added value in better understanding the impact of disease from the patient's perspective has led to the development of instruments to quantify the patients' perception of their health status before and after treatment. Traditional outcomes of treatment for coronary heart disease such as mortality and objective physiological or exercise tests give little information about the impact of either the condition or treatment from the patient's perspective.

Health-related quality of life [HRQL] has been defined by various authors; examples include HRQL as a measure of the patient's perspective representing the "functional effect of an illness and its consequent therapy upon a patient, as perceived by the patient" 3 and that proposed by Patrick and colleagues 4 as "the value assigned to duration of life as modified by the impairments, functional states, perceptions, and social opportunities that are influenced by disease, injury, treatment, or policy". HRQL is now considered an important outcome measure in investigations of therapeutic interventions for patients with chronic conditions such as cancer and heart disease, in epidemiological studies and in patient care, representing a paradigm shift in the assessment of efficacy and effectiveness 5. This paradigm shift is partly a result of the introduction of a "biopsychosocial" perspective in medicine 6. Coronary heart disease is the major cause of disability in many developed regions and by 2020 is forecast to be the major cause of disease burden world-wide 7. Patients who survive an acute coronary event may live for an extended period of time but often may be disabled, helping to drive the increased attention in HRQL outcomes in studies of coronary heart disease 5. As an outcome measure HRQL more pragmatically represents what patients say about how they feel and function in their daily lives as result of a disease or treatment and it generally includes, at a minimum, items about physical function and symptoms, psychological state, and social interaction 348.

When choosing an HRQL instrument, the researcher or clinician needs to ask "has an instrument been developed and tested for the purpose for which it is to be used and does it meet my needs?" Asking this question can give direction to reading the literature and will help the researcher or clinician select the instrument best suited for the specific purpose. There are a number of heart disease specific HRQL instruments. Most are designed for a particular heart disease diagnosis, for example, the Seattle Angina Questionnaire 9, the Minnesota Living with Heart Failure questionnaire 10, the Kansas City Cardiomyopathy Questionnaire 11, and the recently published Myocardial Infarction Dimensional Assessment Scale 12.

For HRQL instruments to be useful, not only must they demonstrate acceptable validity criteria, they must also exhibit good discriminative, evaluative, and predictive properties 13. A discriminative instrument is designed to distinguish between individuals or groups at a single point in time, e.g., good and poor HRQL, and needs to demonstrate reliability. An evaluative instrument is used when one needs to measure change in HRQL over time, e.g., as a result of an intervention, and needs to be responsive. A predictive instrument classifies individuals into a set of predefined measurement categories, e.g., alive or dead. Another key property of both discriminative and evaluative instruments is interpretability, i.e., can the differences between subjects at a single point in time be identified by discriminative instrument as trivial, small, moderate, or large and can the changes within subjects over time be identified by evaluative instruments as trivial, small, moderate, or large?

In this article, we review evidence concerning the measurement properties of the MacNew Heart Disease Health-related Quality of Life [MacNew] Questionnaire 1415. This instrument is a modification of the Quality of Life after Myocardial Infarction [QLMI] Questionnaire which was originally developed nearly 20 years ago for patients who had survived an acute myocardial infraction [MI] and who were referred for subsequent cardiac rehabilitation 16.

The original interviewer-administered QLMI was developed for use in a trial of cardiac rehabilitation in moderately anxious and/or depressed patients with a documented MI 16. It was designed to assess a patient's feelings about a range of issues and concerns identified by individuals who have suffered an acute MI and includes items addressing physical [and somatic], psychological, and social domains. The QLMI was designed to evaluate how daily activities, as well as physical, emotional, and social functioning are affected by the disease and its treatment for the disease.

The original QLMI items were generated through interviews with physicians, nurses, allied health professionals, patients with MI, and by reviewing the literature 17. The item reduction instrument consisted of 97 items. It was administered to a group of 63 patients who were recruited from a cardiac rehabilitation program, 3 community hospitals, and volunteer patients from the community. There were 57 males and 6 females (mean age 58.0 years) who had recovered from an acute MI, 59% within 3 months, 25% 3 to 6 months, and 6% >12 months previously. Patients were asked to identify items of concern to them, and to rate those items from 1 [not very important] to 5 [very important]. A clinical impact score was generated by multiplying the number of patients rating an item as of concern by the mean score of that item 18. The items with the highest scores were selected to form the interviewer-administered QLMI Questionnaire. The items of the original QLMI instrument were conceptually assigned to five domains [symptoms, restrictions, confidence, self-esteem and emotion] 17 without including factor analytical strategies to confirm the theoretically assumed five-factor structure. The internal consistency of the original QLMI domains ranges from 0.75 to 0.87 17. A priori hypotheses to determine the discriminative and evaluative validity of the items in the QLMI were tested against several well established clinical measures [e.g. State-Trait Anxiety Inventory, Beck Depression Inventory, Profile of Mood Scale, Time Trade-off, Quality of Well-Being, Katz social functioning instrument, and a symptom limited exercise test]. Twenty-eight out of 34 hypotheses were accepted confirming the discriminative construct validity of the items 17. Although the evaluative validity of the QLMI was not as robust as its discriminative validity 17, the responsiveness of the instrument has since been demonstrated in a number of studies [see the section on responsiveness below].

The MacNew Heart Disease HRQL questionnaire [MacNew] is a self-administered modification of the original QLMI instrument 1415. The MacNew consists of 27 items which fall into three domains [a 13-item physical limitations domain scale, a 14-item emotional function domain scale, and a 13-item social function domain scale]. There are 5 items that inquire about symptoms: angina/chest pain, shortness of breath, fatigue, dizziness, and aching legs. The time frame for the MacNew is the previous two weeks.

Scoring of the MacNew is straight-forward. The maximum possible score in any domain is 7 [high HRQL] and the minimum is 1 [poor HRQL]. Missing responses do not contribute to the score and item 27, 'sexual intercourse', may be excluded without altering the domain score as each domain score is calculated as the average of the responses in that domain. For example, if only 10 of the 14 Emotional items are answered, the Emotional Score is the average of 10 responses. If more than 50% of the items for a domain are missing, the score for that domain is not calculated, that is, it is considered to be missing. The instrument also has a global HRQL score which can be calculated as the average over all scored items unless one of the domains is completely missing 1415. In addition to the 11 studies reported below which provide psychometric data 1415171920212223242526, the MacNew has been successfully administered, to our knowledge, in at least 12 clinical and/or experimental studies 162728293031323334353637 to more than 5,200 patients with heart disease

A disease specific HRQL instrument is one step towards individualizing the measurement of a patient's quality of life 38. As either a discriminative or evaluative instrument it should meet the basic criteria for acceptable psychometric properties which include validity, reliability, responsiveness, and interpretability 39.

The MacNew has a low respondent-burden 14152326 taking on average 10 minutes or less to complete, and its acceptability is demonstrated by response rates of over 90%. With the availability of SPSS-Syntax to score the MacNew, there is also little researcher-burden.

The MacNew is copyrighted by the developers for the purpose of maintaining an unmodified version in order to preserve the integrity of the instrument. As the MacNew is considered to be in the public domain, there is no cost for permission to use the MacNew or its translations. However, there is a request that investigators use the relevant citations in their publications and provide the developers of the MacNew with published data to further develop the instrument.

The original English version of the MacNew and its translations into Chinese [Cantonese], Danish, Dutch, Farsi, Finnish, French, German, Greek, Hebrew, Italian, Lithuanian, Norwegian, Polish, Portuguese, Romanian, Russian, Spanish, Swedish and Turkish are available from the developers of the MacNew. The basic descriptive information on the MacNew is available on the QOLID website at http://www.qolid.org/.

HRQL provides researchers and clinicians with valuable additional information about the impact of either the condition or treatment from the patient's perspective, particularly in chronic diseases such as coronary heart disease which is a major cause of disability. We believe that the MacNew Heart Disease Health-related Quality of Life instrument meets the established criteria for the psychometric properties of instrument reliability, validity, and responsiveness for use in patients with myocardial infarction and in patients with angina. The English and the German MacNew are presently being tested, with considerable preliminary promise, in patients with heart failure. Psychometric assessment of the German MacNew in pacemaker patients is nearing completion. Further, tests of the psychometric properties of eleven of the MacNew translations are underway in patients with myocardial infarction, with angina, and with heart failure in an international study which is being coordinated through the Working Group on Cardiac Rehabilitation and Exercise Physiology of the European Society of Cardiology.

The MacNew package containing a brief description of the instrument, citations, the scoring algorithm, and the MacNew questionnaire can be obtained from the following:

Neil Oldridge, PhD

Center for Urban Population Health

University of Wisconsin-Milwaukee

1020 N. 12th Street, OHC 4th Floor

Milwaukee, WI 53201-0342

Telephone: 414-219-4084

Fax: 414-219-6563

Email neilb@uwm.edu

GG and NBO developed and validated the original QLMI; LL modified the QLMI as the MacNew and validated it; SH validated the German MacNew and prepared the initial draft of this manuscript; SH, LL, GG, and NBO jointly edited the draft manuscript. All authors have read and approve the manuscript.