TABLE 8.1. Chronic Ear Survey (CES) | ||||||||||||||||||||||||||||||||||
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Outcomes Measurements for Ear Surgery
Outcomes Measurements for Ear Surgery
Pa-Chun Wang
Richard E. Gliklich
Joseph B. Nadol Jr.
QUALITY OF LIFE
Although the evaluation of ear disease has largely relied on the physical and audiologic examination, measurement of treatment success has always included patient-related quality-of-life issues such as the elimination of disease, the achievement of a dry ear, and hearing improvement. Yet other than clinician impression, the rigorous assessment of patient-perceived quality of life has been largely neglected (1,2). Clearly the inclusion of patient-oriented outcomes information will enhance our understanding of the impact of ear disease and the success of treatment (3,4). The development of valid and reliable measures of ear-specific quality of life is the first step in this process. This chapter assesses how far we have come and how far we still must go in measuring the patient’s view of ear disease and its treatment.
EFFICACY VS. EFFECTIVENESS
If efficacy is the ability of a specified treatment to achieve a specified result in an experimental setting, then effectiveness is the ability to achieve that result in the real world. The treatment of chronic ear disease is a complex and individualized mix of patient instructions, medications, and procedures. Traditional ways of reporting treatment results for ear disease, meaning audiograms and “objective” ear assessments, are typically inadequate for comparing different treatments (5,6). Patient-perceived quality of life offers another approach to measurement that is useful for a disease that has few fatalities but many sufferers. In this paradigm a standard of ear-specific quality of life is established by developing and testing measurements and applying those measurements to normal and diseased populations. In practice, once such measures are available, quality of life is assessed before and after treatment and the change in quality of life is recorded as the impact of the treatment. Theoretically, different treatment modalities can be assessed by comparing patients on the basis of change in standardized measurements of quality of life. With this approach, assessment of quality of life becomes a quantitative measurement with known error and confidence intervals (not unlike an audiogram). As our measurements become quantitative and more precise, they can be used for a range of research and practical applications, including identifying the most effective treatments on the basis of absolute results or cost (7).
Patient-based quality-of-life measurements supplement traditional objective measurements and provide a more complete understanding of the effects of a specific ear condition and its intervention.
OUTCOMES MEASURE
Generic vs. Disease-specific
One approach to measuring quality of life is to combine general and disease-specific measurements or surveys. General measures assess the patient’s general health status along several lines of functioning and well-being ranging from physical activities to mental health. The Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) (7), for example, is one of the most widely used general health surveys (8,9). A disease-specific measure focuses more narrowly on the dimensions of disease perceived by the patient with a particular disease (e.g., chronic otitis media). Because of this focus, disease-specific measures tend to be more sensitive to clinical change than general health measures. Combining the two sets of measures provides a broad inventory of health with both the appropriate sensitivity to measure real clinical change and the flexibility to compare across different diseases (10).
Developing general and disease-specific health measures is in itself a rigorous science termed psychometrics (11). Survey content development, item selection, and measurement validation are performed according to standard processes. Each measure has a set of performance characteristics that denote its reliability, validity, and ability to measure clinical change with adequate statistical power (12).
Disease-specific Measurements for Ear Disease and Surgery
Chronic Ear Survey
The Chronic Ear Survey (CES) is a patient-based measure for the evaluation of chronic otitis media developed by the Clinical Outcomes Research Unit at the Massachusetts Eye and Ear Infirmary (13). The CES (Table 8.1) is a 13-item Likert scale survey using three subscales. The activity restriction (AR) subscale assesses the impact of chronic otitis media (COM) on the patient’s daily life. The symptom subscale (ST) assesses the presence of symptoms such as hearing impairment and drainage. The medical resource utilization subscale (MR) assesses medication usage and office visits.
The CES is a validated chronic ear-specific outcomes measure (13). Test-retest reliability is high, with correlation coefficients ranging from 0.81-0.91 for total scores and subscores. Internal consistency (Cronbach’s alpha measurements) is also high at 0.83 for total score and 0.62, 0.8, and 0.75 for AR, ST, and MR subscores, respectively. The CES also correlates with traditional measures such as hearing tests. Survey items on hearing ability are strongly correlated with pure-tone average in the affected ear. The CES correlates well with other measures of hearing-specific and general health. For example, the hearing portion of the CES questionnaire is strongly correlated (r = 0.54; p = 0.0005) with the Hearing Handicap Inventory for Adults (14,15). The ST and AR sections correlate to the bodily pain and social functioning subscales of the MOS SF-36 general health survey, and the CES total score correlates with the SF-36 general health subscale. The CES also demonstrates sensitivity to clinical change after therapy.