Although estimates of prognosis are best made using mathematical methods that combine information about multiple aspects of the patient’s condition, these have not found widespread acceptance in clinical practice 1).
Wilson and Cleary proposed a conceptual model or taxonomy integrating concepts of biomedical patient outcomes and measures of health-related quality of life. The taxonomy is divided into five levels: biological and physiological factors, symptoms, functioning, general health perceptions, and overall quality of life 2).
The patients' perspective of health outcomes has become important input for assessing treatment effects.
The reviewer must clearly detect the primary and secondary outcomes or endpoints and how they were measured. The outcomes should be clinically relevant to quantify bene t, damage, or risk. While there might be statistical relevance in a finding, it may not be clinically significant for the patient’s treatment.
The instruments or questionnaires used for measurement need to be objective, well described in the literature, and validated for the native language of the patient. The outcome of interest can be positive (percentage of fusion or satisfaction) or negative (complication or dissatisfaction). In diagnostic studies, the outcomes of interest are usually calculations of sensitivity, specificity, and positive and negative predictive value.
The data collection in a prospective method has greater credibility when the result and evolution over time are recorded. The manuscript should describe how many fol- low-up visits were performed and the time points used to measure the outcomes, e.g., pretreatment, posttreatment 1 month, 6 months, 1 year, 2 years, and 5 years. Questions to be answered by the reviewers are:
1) are the outcomes clinically relevant or important to the patients
2) are the instruments or questionnaires for measurement objective
3) are the instruments or questionnaires for measurement well described in the literature to enable a correlation of the results
4) are patient-reported outcomes used or just physiological process or radio- graphic measures
5) are the evaluation instruments appropriate for the study and validated for the language of the country where they will be applied
6) is the outcome assessor (evaluator) blinded
7) how is the data collection performed (prospectively or retrospectively)
8) how many follow-up visits are performed and how many time points are used to measure the outcomes?
The minimum follow-up time must have been established to observe (or not observe) the expected outcome. In a surgical specialty, it is very important to have medium and long-term follow-up. The outcome of a surgical tech- nique or treatment is often modi ed after the rst year or even longer. The question to be answered by the reviewers is: was the timing for observation adequate to detect differences between the groups?
Health care evolution has led to focused attention on clinical outcomes of care. Surgical disciplines are increasingly asked to provide evidence of treatment efficacy. As the technological advances push the surgical envelope further, it becomes imperative that postoperative outcomes are studied in a prospective fashion to assess the quality of care provided 3).
End results of particular health care practices and interventions. End results include effects that people experience and care about, such as change in the ability to function. In particular, for individuals with chronic conditions—where cure is not always possible—end results include quality of life as well as mortality. By linking the care people get to the outcomes they experience, outcomes research has become the key to developing better ways to monitor and improve the quality of care. Supporting improvements in health outcomes is a strategic goal of the Agency for Healthcare Research and Quality (AHRQ, formerly the Agency for Health Care Policy and Research).
In the face of technical difficulties and the cost of collecting health outcomes data from patients directly, many “outcome measures” actually use processes of care or use of services as “proxies” for patient's health states. For example, hospital readmission rate is sometimes referred to as an outcome measure; the underlying theory is that readmission reflects a change in health state. In reality, readmissions can occur for many reasons other than the health state of the patient. A high readmission rate may indicate that the patient's health has deteriorated, or it could indicate another issue, such as a lack of caregivers in the home or a misjudgment about the discharge destination at the time of discharge. A high rate of readmissions could reflect poor care during the first admission, or superior care leading to rescue and a sicker population on average at discharge. Such measures may be considered “proxies for health outcome.”
Are the outcomes clinically relevant or important to the patients?
Are the instruments or questionnaires for measurement objective?
Are the instruments or questionnaires for measurement well described in the literature to enable a correlation of the results?
Are patient-reported outcomes used or just physiological or radiographic measures?
Are the evaluation instruments appropriate for the study and validated for the language of the country where they will be applied?
Is the outcome assessor (evaluator) blinded?
How is the data collection performed (prospectively or retrospectively)?
How many follow-up visits are performed and how many time points are used to measure the outcomes?
Outcomes can be observed in the short term, medium term, and long term.
Short term outcome
Medium term outcome
Long term outcome
The main outcomes are the essential outcomes for decision-making, and are those that would form the basis of a ‘Summary of findings’ table. ‘Summary of findings’ tables provide key information about the amount of evidence for important comparisons and outcomes, the quality of the evidence and the magnitude of effect
There should be no more than seven main outcomes, which should generally not include surrogate or interim outcomes. They should not be chosen on the basis of any anticipated or observed magnitude of effect, or because they are likely to have been addressed in the studies to be reviewed.
Primary outcomes for the review should be identified from among the main outcomes. Primary outcomes are the outcomes that would be expected to be analysed should the review identify relevant studies, and conclusions about the effects of the interventions under review will be based largely on these outcomes. There should in general be no more than three primary outcomes and they should include at least one desirable and at least one undesirable outcome (to assess beneficial and adverse effects respectively).
Main outcomes not selected as primary outcomes would be expected to be listed as secondary outcomes. In addition, secondary outcomes may include a limited number of additional outcomes the review intends to address. These may be specific to only some comparisons in the review. For example, laboratory tests and other surrogate measures may not be considered as main outcomes as they are less important than clinical endpoints in informing decisions, but they may be helpful in explaining effect or determining intervention integrity.
The urgent need for outcomes research was highlighted in the early 1980s, when researchers discovered that “geography is destiny.”