60.1 Introduction

In the early 20th century, the focus of vestibular schwannoma (VS) treatment was mortality reduction.s. Literatur ^,​ s. Literatur In the last five decades, advances in surgical technique, radiation delivery, and a better understanding of the natural history of disease have led to a substantial reduction in disease- and treatment-related mortality. Accordingly, we have witnessed a shift in outcome priorities from life preservation to cranial nerve preservation—namely, facial nerve function and serviceable hearing.s. Literatur ^,​ s. Literatur ^,​ s. Literatur With a relative plateau in cranial nerve outcomes and the understanding that there are many other less tangible factors that significantly affect patient’s well-being, many groups have begun exploring quality-of-life (QoL) outcomes. The growing priority of QoL outcomes in VS is evidenced by a fourfold increase in publications on this topic in the decade after the year 2000, compared to the decade prior.s. Literatur

In 1995, the World Health Organization defined QoL as “an individual’s perception of their position in life in the context of the culture and value system in which they live and in relation to their goals, expectations, standards, and concerns.”s. Literatur When QoL is assessed in the context of overall health and disease, the term health-related quality of life (HRQoL) is commonly applied. HRQoL is a broad, multidimensional concept that looks beyond morbidity and mortality and assesses domains related to physical, mental, emotional, and social functioning in the setting of one’s social environment.s. Literatur Where traditional physician-defined outcome measures such as hearing loss of facial paresis only assess impairment, a temporary or permanent loss of physiological function, QoL assessment moves several steps beyond this to ascertain the impact on overall well-being.

The study of HRQoL is particularly germane to sporadic VS and other benign skull base tumors, where normal life expectancy is anticipated, and treatment remains controversial with multiple viable management options available.s. Literatur ^,​ s. Literatur The objectives of this chapter are to (1) provide an overview of HRQoL as it pertains to VS; (2) review the most commonly utilized HRQoL measures used in the VS literature; (3) explore the concept of the minimum clinically important difference (MCID) in HRQoL measures; (4) examine the impact of diagnosis and treatment on HRQoL; and (5) to discuss future direction of HRQoL research.

60.2 Overview of Health-Related Quality-of-Life Assessment in Vestibular Schwannoma

Broadly, HRQoL assessment tools can be classified into generic or disease-specific measures. Generic, multipurpose instruments are useful for understanding various disease processes in the context of global health and for comparing HRQoL across conditions; however, these instruments commonly lack the sensitivity required to detect subtle changes that may arise from the disease process over time or as a result of treatment.s. Literatur For example, common questions utilized by generic measures may be asked about one’s ability to carry groceries or climb one flight of stairs—inquiries that are not specific to the concerns faced by a VS population.

To date, the great majority of the VS HRQoL literature has utilized the multipurpose 36-Item Short-Form (SF-36) Health Survey and Glasgow Benefit Inventory (GBI).s. Literatur ^,​ s. Literatur ^,​ s. Literatur However, in 2010, Shaffer et al introduced the first disease-specific HRQoL measure, the Penn Acoustic Neuroma Quality of Life (PANQOL) scale.s. Literatur Several recent studies have demonstrated important advantages of the PANQOL over the SF-36 and GBI.s. Literatur ^,​ s. Literatur In 2015, after reviewing HRQoL questionnaire survey data from 642 respondents, Carlson et al found that the PANQOL was far more sensitive toward detecting differences between treatment groups compared to the SF-36, GBI, and the Patient-Reported Outcomes Measurement Information System Global 10 (PROMIS-10) short form.s. Literatur

60.3 Health-Related Quality of Life Instruments

The following are the disease-specific and generic measures that are commonly employed in VS HRQoL assessment. While this chapter is focused on HRQoL in sporadic VS, it is notable that there is currently only one validated disease-specific measure for this population with sporadic tumors, while there are three instruments that have been developed for patients with neurofibromatosis type 2.s. Literatur ^,​ s. Literatur ^,​ s. Literatur

60.4 The Minimal Clinically Important Difference

Several studies assessing HRQoL in VS have demonstrated small, but statistically significant differences between treatment modalities. The question remains whether a several point difference on a 100-point scale really matters clinically. First conceived by Guyatt et al in 1987 and later refined by Jaeschke and colleagues in 1989, the concept of the minimal clinically important difference (MCID) was developed to answer this critical question.s. Literatur ^,​ s. Literatur Today, the MCID is defined as the smallest point difference in HRQOL scores that patients perceive as important, either beneficial or harmful, and that could lead to change in management.s. Literatur

MCID values are established according to a specific disease of interest, using one particular instrument. For example, the MCID for the SF-36 in patients with rheumatoid arthritis will likely be different from the MCID for the SF-36 in patients with VS. Furthermore, the MCID may vary according to study population and clinical context even within a disease. For these reasons, the MCID is often presented with a range, in addition to the point estimate. The methodology behind establishing the MCID is beyond the scope of this chapter; however, two valuable summary articles by King as well as Yost and Eton are available for the interested reader.s. Literatur ^,​ s. Literatur

In a recent publication, anchor- and distribution-based methods were used to determine the MCID for the PANQOL and the SF-36 in patients with sporadic VS.s. Literatur In this study, the median (interquartile range) MCID for the PANQOL total score was 11 points (10–12); and the MCIDs for individual PANQOL domains were as follows: hearing, 6 (5–8); balance, 16 (14–19); facial, 10 (no interquartile range); pain, 11 (10–13); energy, 13 (10–17); anxiety, 11 (5–22); and general, 15 (11–19; Fig. 60‑1 ). The MCID was 7 points (6–11) for the SF-36 Mental Health Summary Scale and 8 (6–10) for the Physical Health Summary Scale (Fig. 60‑2 ). To the authors’ knowledge, no other study to date has determined MCID values for these instruments in VS.