A Comparison of Two Approaches to the Treatment of Chronic Cough: Perceptual, Acoustic, and Electroglottographic Outcomes

A Comparison of Two Approaches to the Treatment of Chronic Cough: Perceptual, Acoustic, and Electroglottographic Outcomes *,†Anne E. Vertigan, †Deborah G. Theodoros, ‡Alison L. Winkworth, and §Peter G. Gibson, *xNewcastle, yBrisbane, and zAustralia

Summary. Voice problems have been reported to occur in association with chronic cough (CC) and can interfere with quality of life. Voice symptoms can improve following behavioral intervention for CC that persists despite medical management; however, formal measures of voice changes have not been reported. The aim of this study was to measure the changes in perceptual, acoustic, and electroglottographic voice characteristics after a SPEech Pathology Intervention Program for CHronic Cough (SPEICH-C) compared to a Healthy Lifestyle Education intervention program (HLE control). Eighty-two participants with CC that was refractory to medical management were randomly allocated to receive either the SPEICH-C or an HLE control. Participants in the SPEICH-C group demonstrated a significant reduction in perceptual ratings of breathy, rough, strain, and glottal fry qualities (P < 0.001) in comparison to the HLE control group. There was a significant improvement between pre- and postintervention maximum phonation time, jitter, and harmonicto-noise ratio values in the SPEICH-C group; however, the magnitude of change was not significantly different between groups. There was no significant change in fundamental frequency, standard deviation of fundamental frequency, phonation range, or closed phase of vocal fold vibration after intervention for either group. These results demonstrated that SPEICH-C can improve perceptual aspects of voice quality suggesting that dysphonia may be a fundamental characteristic of CC. Key Words: Efficacy–Chronic cough–Perceptual voice analysis–Acoustic voice analysis–Electroglottographic analysis.

INTRODUCTION Chronic cough (CC) is defined as a cough that lasts for longer than 8 weeks.1 Although CC is a common problem seen in ambulatory health care settings, most cases respond well to medical intervention. Despite rigorous medical management, however, CC can persist in 12–42% of cases thus exacerbating the morbidity of the condition.2,3 Furthermore, CC has been found to have a negative effect on vocal characteristics such as difficulty speaking on the telephone and hoarse voice quality that subsequently affects quality of life in individuals with this condition.4 Previous research has identified an increased prevalence of laryngeal abnormalities,5 voice symptoms,6 and abnormal perceptual voice characteristics including dysphonia, aphonia, whispery, and harsh vocal qualities7,8 in persons with conditions such as CC. There is evidence that voice symptoms can improve after SPEech Pathology Intervention Program for CHronic Cough (SPEICH-C). In a randomized trial designed to determine the effectiveness of speech pathology intervention in reducing cough symptoms, there was a significantly greater reduction in respiratory, cough, voice, and upper airway sympAccepted for publication January 3, 2007. From the *Speech Pathology Department, John Hunter Hospital, Newcastle, Australia; yDivision of Speech Pathology, University of Queensland, Brisbane, Australia; zSchool of Community Health, Charles Sturt University, Albury, Australia; and the xDepartment of Respiratory and Sleep Medicine, Hunter Medical Research Institute, John Hunter Hospital, Newcastle, Australia. Address correspondence and reprint requests to Anne E. Vertigan, B App Sc(Sp Path), MBA, Hunter Area Health Service, Speech Pathology Department, John Hunter Hospital, Locked Bag 1, Hunter Region Mail Centre, New Lambton, NSW 2310, Australia. E-mail: [email protected] Journal of Voice, Vol. 22, No. 5, pp. 581-589 0892-1997/$34.00 Ó 2008 The Voice Foundation doi:10.1016/j.jvoice.2007.01.001

toms after treatment compared to a control intervention.9 The improvement in voice symptoms was measured via patient self-report but has not been verified by formal perceptual and instrumental analyses. There are some similarities between components of speech pathology programs for behavioral management of CC and vocal hygiene programs for voice disorders.10,11 Vocal hygiene programs typically target among other things, hydration and the reduction of coughing and throat clearing behaviors. Changes in acoustic and perceptual voice measures after vocal hygiene education programs for persons with voice disorders have been reported in the literature11 and may be relevant for individuals with CC. Roy et al11 demonstrated a nonsignificant improvement in jitter, shimmer, and noise-to-harmonic ratio after a vocal hygiene program in teachers with voice disorders. There was also a statistically greater improvement in noiseto-harmonic ratio after the vocal hygiene program in comparison to a control group. Chan10 reported on acoustic outcome measures of a vocal hygiene education program for 12 kindergarten teachers with no history of a voice disorder. Acoustic and electroglottographic analyses showed significant reduction in relative amplitude perturbation and improvements in longterm average spectrograph and duty cycle after the education program compared with a nonsignificant improvement in a control group. It is, however, difficult to determine which components of the vocal hygiene programs may have been responsible for the changes in voice quality in these individuals. Furthermore, these programs were not designed for populations presenting with CC. To date, perceptual and physiological voice changes after treatment for CC have not been reported in the literature. The current study was designed to measure changes in perceptual,

582 acoustic, and electroglottographic voice features in individuals with CC after SPEICH-C compared with Healthy Lifestyle Education intervention program (HLE control). It was hypothesized that persons with CC would demonstrate greater improvement in perceptual, acoustic, and electroglottographic voice measures after the SPEICH-C compared to the HLE control. To test this hypothesis, this study proposed to determine (1) whether individuals with CC who receive the SPEICH-C demonstrate significant improvements in perceptual, acoustic, and electroglottographic voice measures and (2) whether the extent of change in these measures is significantly different between individuals who receive the SPEICH-C versus those who receive the HLE control intervention. METHODOLOGY This study involved a randomized controlled trial to examine the effect of the SPEICH-C on voice quality. Participants were randomized to receive either the SPEICH-C or an equivalent course of healthy lifestyle education and were blinded to their group allocation. Perceptual voice ratings and acoustic and electroglottographic voice measures were compared before and after intervention for the SPEICH-C and HLE control groups. This study was approved by the Hunter Area Research Ethics Committee and the University of Queensland Medical Research Ethics Committee. All participants provided written and informed consent to participate in the study. Participants Potential participants assessed for eligibility in this study included 120 persons with CC that had persisted despite medical treatment. These participants had been referred to the speech pathology department at John Hunter Hospital, New South Wales, Australia, from April 2003 until October 2004 for behavioral management of their CC. Inclusion criteria included (1) chronic coughing that persisted despite medical treatment for conditions associated with CC such as asthma, postnasal drip syndrome (PNDS), gastroesophageal reflux (GER), and withdrawal of angiotensin converting enzyme inhibitors (if used), (2) duration of at least 2 months after medical treatment, (3) severity sufficient for participants to seek medical attention by both general practitioner and respiratory physician, (4) minimum age of 18 years, and (5) ability to travel to John Hunter Hospital. Exclusion criteria included recent upper respiratory tract infection, untreated conditions associated with CC such as allergy, PNDS, asthma, GER, lung pathology, abnormality on chest X-ray, chronic obstructive pulmonary disease, and neurological voice disorder. Six of the 120 potential participants considered for inclusion in this did not meet the inclusion criteria and were excluded from the study. A further 17 potential participants declined consent to participate in the study. Of the remaining 97 participants, 47 were randomly allocated to the SPEICH-C group and 50 to the HLE control group. One participant in the SPIECH-C group and four in the HLE control group did not commence their respective intervention programs due to unexpected family responsibilities and spontaneous resolution of symptoms before

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treatment commenced. Three participants in the SPEICH-C group and two in the HLE control group discontinued intervention through failure to contact or attend appointments. A further two participants in each group were unable to attend for their postintervention perceptual and instrumental voice analysis. Thus, 40 participants were included in the SPEICH-C group and 42 in the HLE control group. The mean age of participants was 54.5 years (SD ¼ 17.1, R ¼ 19–84). Sixty-one participants were female and 22 were male. Forty-two participants had a coexisting diagnosis of paradoxical vocal fold movement (PVFM). Data acquisition Participants received an assessment before (pre) and after (post) intervention for CC. Speech samples for each participant were obtained for perceptual analysis by reading the Grandfather passage,12 which was recorded by a Studio Condenser Microphone NT3 (RODE, Rhodes, Australia) positioned 10 cm from the mouth and recorded directly into a personal computer. Acoustic analysis was conducted on sustained vowels using the Praat acoustics analysis program Version 3.9.27 (Boermsa & Weenick 1993) with signal input from a Studio Condenser Microphone NT3 (RODE) positioned 10 cm from the mouth. Samples were recorded directly into a personal computer with a sampling rate of 44.1 kHz. Sustained vowels were elicited by participants being instructed to take a deep breath in and say /a/ for as long as they possibly could at a comfortable pitch and loudness level.13,14 This task was performed three times. Electroglottographic analysis was conducted using the Laryngograph Speech Studio, Laryngograph, UK. In this task, participants wore a head set microphone set at a standard distance (5 cm) while two electrodes attached to a neckband were placed either side of the thyroid cartilage and fastened into position. Electrode placement was checked before recording using vowel prolongations to ensure maximum amplitude of the waveform. Speech samples for each participant were obtained for electroglottographic analysis by reading the extended Rainbow Passage.15 Perceptual voice analysis The connected speech samples were copied onto a master CD and deidentified. The order of these speech samples was randomized across SPEICH-C and HLE control groups and across pre- and postintervention. An additional 34 recordings or 20.5% of the speech samples were randomly selected and repeated. Seventeen of the repeated recordings were from preintervention and a further 17 were from postintervention. These repeated speech samples were inserted randomly among the 166 speech samples to determine intrarater reliability. Thus, a total of 200 samples were recorded onto the listening CD. Two experienced speech pathologists not connected to the study or to the assessment or treatment of the participants, served as listeners and conducted ratings on the speech samples. Listeners were blinded to the participant’s treatment allocation and whether the recording represented a pre- or postintervention condition. Before rating, the speech pathologists completed 2 hours of training in perceptual voice analysis using A

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Sound Judgement program (2007, Latrobe University & Flinders University).16 Speech samples were rated by the two speech pathologists using the perceptual voice profile from A Sound Judgement.16 Fifteen perceptual dimensions of voice were assigned a severity rating from 1 representing normal to 6 representing severely impaired. The listeners rated the voice samples freefield in a quiet room and were permitted to listen to each recording twice if desired. The listeners controlled playback of the voice samples and were not permitted to confer during the rating sessions. Each listener completed the perceptual voice profile for each of the 200 voice samples. The ratings between the two speech pathologists were compared. The speech pathologists were in exact agreement or within ±1 point on the rating scale for 94% of parameters. A Spearman’s rank correlation coefficient indicated moderate correlation between the ratings of the two speech pathologists (rho ¼ 0.580, P < 0.001). The parameters on which the speech pathologists differed by more than 1 point on the rating scale were rerated in a subsequent session where the two speech pathologists conferred to produce a single consensus rating for each of the parameters. The consensus ratings were used in the statistical analyses of the results. Intrarater reliability was calculated using the 34 samples that were repeated on the CD and thus rated twice by each of the two speech pathologists. Intrarater reliability was 95% for rater one and 97% for rater two using ±1 severity scale value. Acoustic and electroglottographic analyses Acoustic measures included maximum phonation time (MPT) measured in seconds, standard deviation of fundamental frequency (SDF0) measured in Hertz (Hz), jitter measured in percentage (%), and harmonic-to-noise ratio (HNR) measured in decibels (dB). The steady state vowel portion as judged by the fundamental frequency trace with a minimum of 3 seconds was chosen for each vowel. The average value of each measure across the three samples was calculated for every participant. A further measure, phonation range (PR) was calculated using a scale task whereby participants phonated an ascending scale on the phoneme /i/. Electroglottographic analysis was conducted on a 2-minute sample of connected speech during a reading task. The data analyzed from this sample included fundamental frequency (Hz) in connected speech (DFx) and duration of the closed phase (%) in each cycle of vocal fold vibration (Qx). Intervention After the preintervention perceptual and instrumental voice analysis, participants were randomized to receive either the SPEICH-C or the HLE control intervention. A random number between 0.000 and 0.999 was computer generated and given to the treating speech pathologist once the participant had consented to the study. Participants with numbers between 0.000 and 0.499 received the HLE control program, whereas those with numbers between 0.500 and 0.999 received the SPEICHC program. The treating speech pathologist was aware of each participant’s group allocation but was not involved in the

583

allocation process. Group allocation was concealed from participants until the conclusion of the postintervention assessment. The intervention for both SPEICH-C and HLE control groups involved four 30-minute intervention sessions provided by qualified speech pathologists with experience in treating voice disorders. The SPEICH-C involved four components including education about the nature of cough, strategies to control the cough, psychoeducational counseling, and vocal hygiene education to reduce laryngeal irritation.9 Written handouts were provided in the initial treatment session and the content was explained by the treating speech pathologist. Specific issues were explored in further detail during subsequent sessions according to the needs of the individual participant. The education component included information regarding the rationale for a behavioral approach to managing their cough. Firstly, the goal of behavioral management is suppression of the cough even when there is a sensation of needing to cough or clear phlegm. Secondly, there is a lack of physiological benefit from repeated coughing as opposed to acute cough where there is a physiological need. Thirdly, there are negative side effects from repeated coughing including laryngeal trauma, exacerbation of irritation, and perpetuation of the cycle of coughing. Finally, information was given on the nature of neural control of the cough in that while cough is a reflex, it can be brought under voluntary control.17 Participants were taught specific strategies to inhibit their cough by identifying when a cough was about to occur and implementing a strategy to suppress or replace the cough. Two main techniques were taught that involved suppression of the cough. The first involved substituting the cough for an effortful swallow using head flexion and the Valsalva swallow.18 This swallow could be implemented as a dry swallow or with a sip of water. The second technique involved substituting the cough for the pursed lip breathing technique as described by Blager et al.19 This technique involved breathing out through pursed lips to maximize expiratory flow through the larynx. Other distracting techniques used when anticipating the need to cough included drinking water, sucking ice, chewing gum, attempting to delay the cough, and sucking nonmedicated lollies to increase the frequency of saliva swallows. The vocal hygiene education included advice aimed to reduce laryngeal irritation and maximize hydration to reduce stimulation of cough receptors. The content of this education included advice to avoid smoking or exposure to passive smoke; minimize consumption of substances known to have a drying effect on the larynx such as alcohol, caffeine, and medicated cough lozenges; increase systemic and surface hydration through steam inhalation; and increasing the volume and frequency of water intake and strategies for behavioral management of GER. Vocal hygiene information was provided verbally and in writing with specific strategies discussed for individual participants. The rationale for each component of vocal hygiene was discussed and participants were given the opportunity to discuss and explore any specific issues surrounding the implementation of the strategies. The psychoeducational counseling addressed some differences between behavioral and medical treatment and aimed

584 to facilitate acceptance of a behavioral approach.8 In speech pathology treatment, the patient has the ultimate responsibility for controlling symptoms in contrast to medical treatment where medication is largely responsible for symptom control. Participants were encouraged to internalize control over their cough and view the cough as something they did in response to irritating stimuli rather than a phenomenon outside of their control. Participants were also encouraged to set realistic goals, recognize that treatment is demanding, understand that there was no easy cure, and that results may not be observed immediately. These issues were addressed through counseling and education. The HLE control program consisted of four components of healthy lifestyle education including relaxation, stress management, exercise, and diet. Each component of the HLE control program was covered at least once during the course of therapy. Written handouts were provided at each session. The relaxation component included providing information regarding the principles of relaxation, introduction to some basic types of relaxation, and exercises in progressive relaxation.20 Exercises for ideational and total body relaxation were provided for home practice. Ideational relaxation involved the participant imagining a peaceful scene or environment and focusing on maintaining the physical sensations such as breathing and muscle tension associated with that environment. The healthy eating component focused on adequate intake of a variety of food groups including meat and meat substitutes, dairy, fruit and vegetables, and starchy carbohydrates while reducing refined sugar, fat, and alcohol. The information was provided through verbal explanation, discussion, and handouts. Participants kept a diary of their food intake for 1 week and this was reviewed at the following session. The exercise component included information on general principles of exercise, safety guidelines, and suggestions for exercise methods such as walking or swimming for various levels of fitness. A program of gentle body stretches was included and these were demonstrated for the participant. Participants were advised to practice the stretches at home and to consider increasing their level of physical activity. The stress management program included information on various types of stress with a distinction made between factors that are within versus outside of an individual’s control. Several strategies for managing the stress were provided in verbal and written format. These included information on getting adequate sleep, time-outs and leisure, physical contact, support systems, realistic expectations, reframing, belief systems, and humor. Data analysis Data were analyzed using a two-way repeated measures ANOVA examining main effects for time (ie, pre- vs postintervention) and intervention (ie, SPEICH-C vs HLE control) and the time by intervention interaction effect. The time by intervention interaction effect was the principle test comparing the two treatments. Post hoc analyses were conducted using t tests. Preintervention equivalence was determined by examining the main effect for intervention. Post hoc testing of preintervention values was conducted using an independent t test between groups.

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RESULTS There was an equivalent distribution of participants into SPEICH-C and HLE control groups according to gender and age. The SPEICH-C group contained seven males and 33 females, whereas the HLE control group contained 15 males and 28 females. The mean age for participants in the SPEICH-C group was 58.9 years (SD ¼ 13.6) and in the HLE control group 61.5 years (SD ¼ 13.3). Twenty-two participants in the SPEICHC group and 20 in the HLE control group had a coexisting diagnosis of PVFM. An independent t test indicated no significant difference between groups in age between groups (t ¼ 1.003, P ¼ 0.319). The chi square test indicated no significant difference between groups in gender distribution (c2 ¼ 3.215, df ¼ 1, P ¼ 0.073) or presence of PVFM (c2 ¼ 1.002, df ¼ 1, P ¼ 0.317). There was no significant difference in any preintervention measures between participants with CC and PVFM and those with CC without PVFM (Appendices A and B). Perceptual voice analysis Pre- and postintervention perceptual voice ratings are reported in Table 1. There was a significant improvement in breathy, rough, strained, and glottal fry vocal qualities with the SPEICH-C intervention, when compared to the HLE control intervention as determined by the significant time by intervention interaction effect. In the analysis of voice arrests, there was a significant time by intervention interaction effect indicating that the improvement in this feature was significantly greater in the SPEICH-C than the HLE control group. However, there was no significant main effect for time or intervention in the analysis of voice arrests. The remaining perceptual voice features (low pitch, high pitch, monotone, soft, loud, pitch breaks, phonation breaks, tremor, falsetto, and diplophonia) demonstrated no significant treatment effects. The main effect for time was also significant in the analysis of breathy, rough, strained, and glottal fry qualities. Post hoc analysis indicated a significant pre- to postintervention improvement in these qualities in the SPEICH-C group (breathy: t ¼ 5.585, P < 0.001; strain: t ¼ 5.516, P < 0.001; rough: t ¼ 5.372, P < 0.001; glottal fry: t ¼ 4.295, P < 0.001) but not the HLE control group (breathy: t ¼ 0.147, P ¼ 0.884; strain: t ¼ 0.644, P ¼ 0.524; rough: 1.347, P ¼ 0.186; glottal fry: t ¼ 0.829, P ¼ 0.412). There was a significant main effect for intervention for the features, low pitch and breathy. Post hoc analysis of low pitch values indicated no significant difference between the SPEICH-C and HLE control groups in either preintervention (t ¼ 1.768, P ¼ 0.081) or postintervention (t ¼ 1.932, P ¼ 0.058) values. Post hoc analysis of breathy values indicated no significant difference between the SPEICH-C and HLE control groups in preintervention values (t ¼ 0.136, P ¼ 0.892) but that postintervention values were significantly lower in the SPEICH-C than the HLE control group (t ¼ 4.309, P < 0.001). Therefore, preintervention values between groups could be considered equivalent. Acoustic and electroglottographic analyses Pre- and postintervention acoustic and electroglottographic values are reported in Table 2. The MPT increased by 1.7

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Two Approaches to Common Cough Treatment

TABLE 1. Pre- and Postintervention Analysis of Perceptual Voice Ratings for the SPEICH-C and HLE Control Groups Timey Pre M (SD) Post M (SD) Difference (SD) High pitch

SPEICH-C Control Low pitch SPEICH-C Control Monotone SPEICH-C Control Soft SPEICH-C Control Loud SPEICH-C Control Breathy SPEICH-C Control Strain SPEICH-C Control Rough SPEICH-C Control Glottal fry SPEICH-C Control Pitch breaks SPEICH-C Control Phonation breaks SPEICH-C Control Voice arrests SPEICH-C Control Falsetto SPEICH-C Control

1.0 (0.2) 1.0 (0.2) 1.2 (0.5) 1.4 (0.6) 1.3 (0.5) 1.2 (0.5) 1.3 (0.8) 1.3 (0.6) 1.0 (0.2) 1.0 (0.0) 2.4 (1.2) 2.4 (1.2) 2.7 (1.3) 2.6 (1.0) 2.7 (1.2) 2.6 (1.1) 2.1 (1.2) 2.0 (1.2) 1.1 (0.5) 1.1 (0.3) 1.1 (0.6) 1.1 (0.3) 1.1 (0.6) 1.0 (0.0) 1.0 (0.2) 1.0 (0.0)

1.1 (0.5) 1.0 (0.2) 1.1 (0.4) 1.3 (0.7) 1.2 (0.6) 1.2 (0.4) 1.1 (0.5) 1.1 (0.4) 1.0 (0.0) 1.0 (0.0) 1.5 (0.9) 2.4 (1.0) 1.9 (1.1) 2.6 (1.0) 1.9 (1.2) 2.8 (1.1) 1.3 (0.7) 2.1 (1.1) 1.0 (0.0) 1.1 (0.2) 1.0 (0.0) 1.0 (0.2) 1.0 (0.0) 1.1 (0.4) 1.0 (0.0) 1.0 (0.0)

0.1 (0.5) 0.0 (0.2) 0.1 (0.6) 0.0 (0.6) 0.1 (0.6) 0.1 (0.4) 0.1 (0.7) 0.2 (0.7) 0.1 (0.2) 0.0 (0.0) 0.9 (1.1) 0.1 (1.1) 0.8 (1.0) 0.2 (1.0) 0.8 (1.0) 0.2 (1.0) 0.1 (0.5) 0.2 (1.2) 0.1 (0.5) 0.0 (0.4) 0.14 (0.6) 0.09 (0.3) 0.1 (0.6) 0.1 (0.4) 0.0 (0.2) 0.0 (0.0)

F

P

Interventionz Time 3 Interventionx F

P

F

P

1.218 0.273

0.846 0.360

1.218

0.273

0.836 0.363

4.986 0.024*

0.019

0.899

1.335 0.251

0.147 0.702

0.081

0.777

3.683 0.059

0.003 0.954

0.009

0.902

0.906 0.344

0.906 0.344

0.906

0.344

13.724 <0.001* 4.429 0.042*

15.367

<0.001*

10.024 0.002* 1.567 0.214

17.127

<0.001*

8.357 0.005* 2.223 0.140

22.725

<0.001*

5.664 0.020* 2.926 0.091

12.769

0.001*

1.578 0.213

0.145 0.705

0.509

0.478

2.829 0.096

0.108 0.744

0.605

0.439

0.358 0.551

0.551 0.358

4.275

0.042*

0.906 0.344

0.906 0.344

0.906

0.344

Notes: All participants received a normal rating for the features tremor and diplophonia. * Significant at P < .05. y Main effect for time. z Main effect for intervention. x Interaction effect between time and intervention.

seconds in the SPEICH-C group compared with 0.7 seconds in the HLE control group. There was no significant intervention by time interaction effect and no main effect for intervention. There was a significant main effect for time (Table 2). Post hoc analysis indicated that the pre- to postintervention improvement was significant for the SPEICH-C group (t ¼ 2.180, P ¼ 0.035) but not for the HLE control group (t ¼ 1.088, P ¼ 0.283). There was a reduction in mean jitter values of 0.9% in the SPEICH-C group compared with 0.3% in the HLE control group. There was no significant time by intervention interaction effect and no main effect for intervention but a significant main effect for time (Table 2). Post hoc analysis indicated that the main effect for time was significant for the SPEICH-C group (t ¼ 2.095, P ¼ 0.043) but not for the HLE control group (t ¼ 1.324, P ¼ 0.193). Similar to jitter values, there was an increase in HNR after intervention for participants in the SPEICH-C group compared with a slight decrease in HNR values (1.2 dB) for the HLE control group. There was no significant time by intervention interaction effect and no main effect for intervention but a significant main effect for time (Table 2). Post hoc analysis indicated a significant improvement in

pre- to postintervention HNR values in the SPEICH-C group (t ¼ 3.429, P ¼ 0.001) compared with no significant improvement in the HLE control group (t ¼ 1.241, P ¼ 0.222). There was a significant main effect for intervention in the analysis of SDF0 results. Post hoc analysis indicated that preintervention SDF0 values were significantly higher in the SPEICH-C than the HLE control group (t ¼ 2.180, P ¼ 0.035). There was no significant difference in postintervention values between groups (t ¼ 1.852, P ¼ 0.068). There was a slight decrease in SDF0 after intervention for both SPEICH-C and HLE control groups. However, there was no main effect for time and no time by intervention interaction effect (Table 2). Analysis of PR, DFx, and Qx values demonstrated no significant main effect for time or intervention and no time by intervention interaction effect (Table 2). These results indicate that with the exception of SDF0, preintervention values were equivalent between groups.

DISCUSSION This study used the most comprehensive voice assessment protocol in participants with CC to date and demonstrated a greater

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TABLE 2. Pre- and Postintervention Analysis of Acoustic and Electroglottographic Measures for the SPEICH-C and HLE Control Groups Timey Pre M (SD) Post M (SD) Difference M (SE) MPT

SPEICH-C 9.4 (6.4) 11.0 (5.6) Control 10.8 (6.4) 11.6 (6.6) SDF0 SPEICH-C 18.6 (12.3) 17.7 (14.2) Control 25.0 (16.2) 23.7 (17.3) Jitter SPEICH-C 2.6 (2.5) 1.6 (1.3) Control 2.4 (1.6) 2.1 (1.5) HNR SPEICH-C 17.1 (5.9) 19.7 (5.0) Control 19.0 (5.1) 18.6 (5.5) PR SPEICH-C 17.5 (7.5) 20.3 (6.8) Control 18.6 (8.3) 19.3 (6.7) DFx (male) SPEICH-C 97.3 (13.1) 96.7 (12.3) Control 105.7 (16.6) 103.0 (16.3) DFx (female) SPEICH-C 167.4 (27.1) 167.7 (21.6) Control 178.3 (29.8) 177.1 (32.0) Qx SPEICH-C 39.3 (17.9) 43.4 (19.5) Control 33.2 (16.6) 37.2 (19.0)

1.7 (0.7) 0.7 (0.7) 1.0 (2.6) 1.2 (2.5) 0.9 (0.4) 0.3 (0.2) 2.6 (0.8) 1.2 (0.9) 2.8 (1.3) 0.7 (1.1) 0.7 (2.2) 2.7 (4.0) 0.3 (3.7) 1.2 (4.5) 4.1 (3.4) 4.0 (2.4)

F

Interventionz P

F

P

Time 3 Interventionx F

P

5.392 0.023* 0.616 0.254

0.650

0.422

0.423 0.517

0.001

0.970

6.266 0.014* 1.606 0.513

1.606

0.209

10.012 0.002* 0.171 0.681

1.667

0.200

5.418 0.022*

3.488 0.066

0.029 0.866

1.132

0.291

0.292 0.597

0.897 0.360

0.109

0.746

0.023 0.881

1.977 0.166

0.064

0.801

1.147 0.288

0.207 0.651

0.581

0.449

Abbreviations: MPT, maximum phonation time; SDF0, standard deviation of fundamental frequency; HNR, harmonic-to-noise ratio; PR, phonation range; DFx, distribution of fundamental frequency in connected speech; Qx, closed phase of vocal fold vibration; SE, standard error. *Significant at P < .05. SE ¼ Standard error. y Main effect for time. z Main effect for intervention. x Interaction effect between time and intervention.

improvement in perceptual voice measures following the SPEICH-C than the HLE control intervention. There were also significant improvements in pre- to postintervention acoustic measures of MPT, jitter, and HNR for the SPEICH-C group; however, the extent of these changes was not significantly different between groups. A summary of treatment outcomes is reported in Table 3. There was no significant difference in preintervention measures between the SPEICH-C and HLE control groups with the exception of perceptual ratings of low pitch and SDF0. Although there were some differences in preintervention Qx and DFx values, these did not reach statistical significance. Likewise, although the SPEICH-C group had a lower proportion of male participants, this proportion only approached statistical significance. Due to the randomization procedure, these differences occurred by chance. However, it is possible that these preintervention differences may have influenced the outcomes observed. The acoustic and perceptual measures that did demonstrate significant change after intervention were equivalent between the SPEICH-C and HLE control groups at preintervention. Therefore, it could be assumed that the differences observed after intervention were due to the intervention rather than intrinsic preintervention differences between groups. Perceptual voice analysis Results of the perceptual voice analysis supported the hypothesis that the SPEICH-C program was more effective than the HLE control program in reducing deviant voice features associ-

ated with CC. The parameters that improved after intervention in the SPEICH-C group were breathy, rough, strained, and glottal fry suggesting that particular aspects of voice quality might respond to intervention. Breathy, rough, and strained qualities have been noted to be impaired in comparison to healthy controls21 so that the qualities that responded to intervention were those that were impaired before treatment. In contrast, perceptual ratings of pitch and loudness demonstrated limited significant change after intervention and were not significantly different from the healthy controls reported previously.21 These results could imply that physiological factors associated with voice quality such as vocal fold closure and regularity of vocal fold vibration could improve after intervention, whereas factors associated with pitch such as the length, mass, and tension of the vocal folds may remain unaffected. There was a significant time by intervention interaction effect for the feature of voice arrests. This result suggests that the degree of improvement in voice arrests was significantly greater in the SPEICH-C group than the HLE control group. However, voice arrests are not a prevalent feature of CC21 and there was no significant main effect for time for this vocal feature. Therefore, the significant difference might be a statistical aberration and should be interpreted with caution. There are several possible reasons for vocal quality changes to occur after the intervention for the CC. It is possible that the aberrant voice quality could be integral to the condition of CC and that effective treatment of CC will result in voice improvements. This hypothesis is consistent with French et al4 who

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TABLE 3. Summary of Outcomes for the SPEICH-C and HLE Control Groups

Perceptual

Acoustic

Electroglottographic

Quality Pitch Loudness MPT Jitter HNR PR DFx Qx

SPEICH-C

HLE Control

SPEICH-C Versus HLE Control

Y X X Y Y Y X X X

X X X X X X X X X

YY XX XX XX XX XX XX XX XX

Abbreviations: MPT, maximum phonation time; HNR, harmonic-to-noise ratio; PR, phonation range; DFx, fundamental frequency in connected speech; Qx, closed phase of vocal fold vibration; Y, significant improvement from pre- to postintervention; X, no significant improvement form pre- to postintervention; YY, improvement significantly higher in the SPEICH-C than HLE control group; XX, no significant difference in improvement between SPEICH-C and HLE control groups.

reported that negative side effects of CC, including those related to voice use, improved after effective medical treatment of the CC. Another possibility is that vocal fold edema caused by repeated coughing resolved after effective treatment of the CC in the current study.22 However, endoscopic evaluation of the larynx before and after intervention would be needed to confirm this hypothesis. A further reason for the improvement in voice quality after the intervention program relates to throat irritation and cough hypersensitivity. Laryngeal irritation and cough sensitivity in persons with CC could result in laryngeal tension as an attempted protective mechanism thus leading to impaired voice quality.23,24 It is possible that cough hypersensitivity and a sensation of laryngeal irritation were reduced after the intervention program. This hypothesis would be consistent with Smith et al25 who found that cough sensitivity in healthy volunteers decreased after instruction to suppress coughing. Effective treatment of CC could reduce laryngeal irritation and tension manifesting as improved vocal fold closure and regularity of vocal fold vibration and subsequently a reduction in features such as breathiness, roughness, and strain. Another possible consequence of reduced cough sensitivity after treatment could be related to stimulation of the cough receptors. It has been hypothesized that breathy voice quality and shorter closed phase of vocal fold vibration could be due to attempts to reduce stimulation of the cough receptors during phonation that trigger coughing.21 Successful treatment of the cough could be associated with a decreased tendency to avoid stimulation of the cough receptors during phonation thereby reducing breathy and strained vocal qualities. However, the lack of significant change in Qx data noted in the current study does not support this hypothesis. One component of the SPEICH-C program involved maximizing hydration. Improving hydration has been shown to reduce phonation threshold pressure26 and increase resistance of the vocal folds to injury.27,28 Reducing phonation threshold pressure may have reduced the effort required to initiate phonation, resulting in less stimulation of the cough receptors. These

physiological characteristics may have improved perceptual features of voice quality. Decreased coughing after treatment may have lessened anxiety in some participants, resulting in reduced extrinsic laryngeal muscle tension and associated qualities such as strain. However, anxiety is not a prevalent feature in many individuals with CC.6,29 Furthermore, this hypothesis is tenuous without postintervention measures of anxiety. Improved perceptual voice features in participants with CC may have been due to a reduction in reflux episodes. There are two possible mechanisms by which reflux episodes may have decreased after the SPEICH-C program. Firstly, the vocal hygiene component of the SPEICH-C involved behavioral management of reflux. Secondly, a reduction in coughing episodes after the SPEICH-C may have resulted in fewer reflux episodes being triggered. The combination of these factors may have reduced the incidence of reflux and associated laryngeal irritation thus leading to improvements in voice quality. Perceptual analysis is considered to be the gold standard of voice assessment and has more immediate clinical significance than acoustic measures. Despite inherent limitations of perceptual analysis that have been reported in the literature, perceptual ratings in the current study were conducted by perceptual listeners who were blinded to both group allocation and intervention status. The listeners used identical procedures for rating all voice samples. Interrater reliability is an inherent problem in perceptual voice analysis and was not high in the current study. However, consensus rating was used as the final rating in order to help to overcome the limitations of interrater reliability. Instrumental voice analysis Acoustic and electroglottographic measures demonstrated less change in voice after the SPEICH-C program with a trend for greater change to be demonstrated by acoustic rather than by electroglottographic measures. Although there were significant improvements between pre- and postintervention MPT, jitter, and HNR values, the degree of improvement was not significantly different between groups. This result may suggest that

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the direct speech pathology treatment was no more effective than healthy lifestyle education in addressing voice symptoms relating to CC. Alternatively, the degree of significance in acoustic measures obtained in the current study could be a manifestation of the acoustic measures themselves or due to insufficient power in the study. The standard deviation for instrumental measures in the current study was large, which may have influenced the power of the study and made group comparisons less sensitive to change (Table 2). Carding et al30 found that acoustic measures such as jitter, shimmer, and noise-to-harmonic ratio had limited sensitivity to change after successful intervention. Further, Carding et al30 reported small effect sizes possibly due to the poor reliability of the acoustic measures. Holmberg et al31 found a significant increase in fundamental frequency after the treatment program for vocal nodules. Interestingly, however, this change did not occur during the vocal hygiene phase of the treatment program but only occurred once direct voicing techniques were introduced. A more favorable outcome in perceptual than the instrumental measures may have been due to the fact that severity of perceptual features decreased but did not return to normal. Furthermore, most of perceptual voice features were in the mild to moderate range in the current study. Acoustic measures may not have been sensitive enough to detect changes in voices of milder severity levels.30

and after successful medical treatment for the CC could clarify whether changes in voice are simply due to a reduction in coughing or whether there are other specific features of CC that effect voice function. As the current treatment program was multifactorial, it is not possible to determine which aspects of the program were responsible for the change in outcomes observed, and further research examining specific components of the program would be needed.

Clinical implications Behavioral treatment for CC can result in improvements in perceptual aspects of voice quality. Vocational, social, and relational variables are likely to influence the degree to which vocal function in persons with CC affects an individual’s quality of life. Some individuals may be predominantly concerned with their cough regardless of the severity of any associated voice symptoms. Therefore, it is important to determine patient’s degree of concern about their voice, establish goals for both cough and voice on an individual basis and use additional specific voice therapy techniques if required. Perhaps formal voice analysis could be recommended as an additional outcome measure in persons undergoing behavioral treatment for CC, particularly when there is evidence of associated PVFM or upper airway hyperresponsiveness. Improvements in voice after the SPEICH-C may contribute to improved quality of life in some individuals with CC.

This study was supported by a grant from Jennifer Thomas through the Hunter Medical Research Institute. Professor Gibson is an NHMRC research fellow. Anne Vertigan holds an NHMRC scholarship through the Centre for Clinical Research Excellence in Respiratory Medicine. The authors would like to acknowledge Megan Barr and Tina Wilkie, Speech Pathologists, John Hunter Hospital for conducting the perceptual ratings.

Future directions Further research using larger participant numbers would be required to further examine the effect of the SPEICH-C on acoustic and electroglottographic voice measures and to overcome the limitation of the power of the study. Further studies could investigate the utility of voice-related outcome measures for individuals with CC. Additional voice measures such as the voice handicap index32 could be used to measure the effect of voicerelated problems. Endoscopic and stroboscopic examination of laryngeal function to provide further information about the underlying physiological changes occurring in the vocal folds after the SPEICH-C could be a useful adjunct to the measures used in the current study. Measuring voice changes before

CONCLUSION There was a significant improvement in perceptual voice features and some improvements in acoustic voice measures after successful behavioral treatment for CC. The improvement in voice after the SPEICH-C would appear to suggest that dysphonia occurring in CC is integral to that disorder possibly due to the cough itself or alternatively due to separate underlying processes such as muscle tension or laryngeal irritation. Further research is needed to confirm the clinical utility of acoustic and electroglottographic measures for measuring change in CC. Comprehensive voice assessment including perceptual, acoustic, and physiological measures is needed to provide a thorough picture of voice function. Acknowledgments

REFERENCES 1. Pratter M, Brightling C, Boulet L, Irwin R. An empiric integrative approach to the management of cough: ACCP evidence-based clinical practice guidelines. Chest. 2006;129(1 Suppl):222S-231S. 2. Haque R, Usmani O, Barnes P. Chronic idiopathic cough: a discrete clinical entity? Chest. 2005;127:1710-1713. 3. Chung F, Widdicombe J, Boushey H, eds. Cough: Causes, Mechanisms and Therapy. Melbourne: Blackwell Publishing; 2003. 4. French C, Irwin R, Curley F, Krikorian C. Impact of chronic cough on quality of life. Arch Intern Med. 1998;158:1657-1661. 5. Bucca C, Rolla G, Brussino L, DeRose V, Bugiani M. Are asthma-like symptoms due to bronchial or extrathoracic airway dysfunction? Lancet. 1995;346:791-795. 6. Vertigan A, Theodoros D, Gibson P, Winkworth A. Voice and upper airway symptoms in people with chronic cough and paradoxical vocal fold movement. J Voice. 2006, Epub. 6. 7. Andrianopoulos M, Gallivan G, Gallivan K. PVCM, PVCD, EPL, and irritable larynx syndrome: what are we talking about and how do we treat it? J Voice. 2000;14:607-618. 8. Vertigan A. Speech pathology management of chronic cough. Acquiring Knowl Speech Lang Hear. 2001;3:62-66. 9. Vertigan A, Gibson P, Theodoros D, Winkworth A. A review of voice and upper airway function in chronic cough and paradoxical vocal cord movement. Curr Opin Allergy Clin Immunol. 2007;7:37–42. 10. Chan R. Does the voice improve with vocal hygiene education? A study of some instrumental voice measures in a group of kindergarten teachers. J Voice. 1994;8:279-291.

Anne E. Vertigan, et al

11. Roy N, Weinrich B, Gray S, et al. Voice amplification versus vocal hygiene instruction for teachers with voice disorders: a treatment outcomes study. J Speech Lang Hear Res. 2002;45:625-638. 12. Darley F, Aronson A, Brown J. Motor Speech Disorders. Philadelphia, PA: WB Saunders; 1975. 13. Hirano M. Clinical Examination of Voice. Vienna: Springer-Verlag; 1981. 14. Baken R. Clinical Measurement of Speech and Voice. Needham Heights: Allyn and Bacon; 1987. 15. Fairbanks G. Voice and Articulation Drill Book. (2nd ed.). New York: Harper & Row; 1960. 16. Oates J, Russell A. Learning voice analysis using a multi-media package: development and preliminary evaluation. J Voice. 1998;12:500-512. 17. Lee P, Cotterill-Jones C, Eccles R. Voluntary control of cough. Pulm Pharmacol Ther. 2002;15:317-320. 18. Logemann J. Evaluation and Treatment of Swallowing Disorders. (2nd ed.). Texas: Pro-ED, Inc.; 1998. 19. Blager FB, Gay ML, Wood RP. Voice therapy techniques adapted to treatment of habit cough: pilot study. J Commun Disord. 1988;21:393-400. 20. Bernstein D, Borkovec T. Progressive Relaxation Training: A Manual for the Helping Profession. Champaign, IL: Research Press; 1973. 21. Vertigan A, Theodoros D, Winkworth A, Gibson P. Perceptual voice characteristics in chronic cough and paradoxical vocal fold movement. Folia Phoniatr Logop. In press. 22. Aronson AE. Clinical Voice Disorders: An Interdisciplinary Approach. (2nd ed.). New York: Georg Thieme Verlag Stuttgart; 1985.

APPENDIX A. COMPARISON OF PREINTERVENTION PERCEPTUAL VOICE RATINGS BETWEEN PARTICIPANTS WITH CC AND PVFM AND THOSE WITH CC WITHOUT PVFM USING A MANN-WHITNEY U TEST (U)

U

23. Choudry N, Fuller R. Sensitivity of the cough reflex in patients with chronic cough. Eur Respir J. 1992;5:296-300. 24. Ryan N, Gibson P. Cough reflex hypersensitivity and upper airway hyperresponsiveness in vocal cord dysfunction with chronic cough. Respirology. 2006;11(suppl 2):A48. 25. Smith J, Johnson C, Brammer C, Kalam R, Jones S, Woodcock A. The effect of a psychological intervention on the urge to cough. Am Thorac Soc. 2005;A40:A113. 26. Verdolini-Marston K, Titze I, Druker D. Changes in phonation threshold pressure with induced conditions of hydration. J Voice. 1990;4:142-151. 27. Verdolini-Marston K, Sandage M, Titze I. Effect of hydration treatments on laryngeal nodules and polyps and related voice measures. J Voice. 1994;8:30-47. 28. Titze I. Heat generation in the vocal folds and its possible effect on vocal endurance. In: Lawrence V, ed. Care of the Professional Voice, Park I: Instrumentation in Voice Research. New York: The Voice Foundation; 1981. 29. McGarvey L, Carton C, Gamble L, et al. Prevalence of psychomorbidity among patients with chronic cough. Cough. 2006;2. 30. Carding P, Steen I, Webb A, Mackenzie K, Deary I, Wilson J. The reliability and sensitivity to change of acoustic measures of voice quality. Clin Otolaryngol. 2004;29:538-544. 31. Holmberg E, Hillman R, Hammarberg B, Sodledersten M, Doyle P. Efficacy of a behaviourally based voice therapy protocol for vocal nodules. J Voice. 2001;15:395-412. 32. Jacobson B, Benninger M, Newman C. The Voice Handicap Index (VHI): development and validation. Am J Speech Lang Pathol. 1997;6:66-70.

APPENDIX B. COMPARISON OF PREINTERVENTION ACOUSTIC AND ELECTROGLOTTOGRAPHIC VOICE MEASURES BETWEEN PARTICIPANTS WITH COUGH + PVFM AND THOSE WITH COUGH ALONE USING AN INDEPENDENT t TEST (T)

CC and PVFMCC Without PVFM High pitch Low pitch Monotone Soft Loud Breathy Rough Strain Glottal fry Pitch breaks Phonation breaks Voice arrests Falsetto Tremor Diplophonia

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Two Approaches to Common Cough Treatment

M (SD)

M (SD)

P

1.0 (0.2) 1.3 (0.6) 1.3 (0.5) 1.3 (0.7) 1.0 (0.0) 2.5 (1.3) 2.8 (1.1) 2.8 (1.2) 2.1 (1.3) 1.1 (0.5) 1.2 (0.7)

1.0 (0.2) 1.3 (0.6) 1.2 (0.5) 1.3 (0.8) 1.0 (0.2) 2.2 (1.8) 2.6 (1.3) 2.5 (1.1) 2.0 (1.1) 1.1 (0.2) 1.0 (0.0)

798.5000.972 776.5000.756 776.0000.751 793.0000.920 780.0000.329 708.5000.365 733.5000.511 704.5000.344 790.5000.926 776.0000.590 676.5000.009*

1.2 (0.6) 1.0 (0.0) 1.0 (0.0) 1.0 (0.0)

1.0 (0.0) 1.0 (0.2) 1.0 (0.0) 1.0 (0.0)

738.0000.072 780.0000.329 799.5001.000 799.5001.000

Abbreviations: M, mean; SD, standard deviation; *significant at P < .05.

MPT SDF0 Jitter HNR PR DFx Qx

Cough + PVFM

Cough Alone

M (SD)

M (SD)

t

P

9.7 (5.5) 22.6 (14.2) 2.3 (1.6) 18.1 (4.5) 18.9 (7.4) 157.3 (39.4) 34.0 (15.8)

10.6 (7.4) 21.1 (15.4) 2.7 (2.5) 16.4 (6.2) 16.9 (8.2) 150.6 (41.8) 38.4 (19.0)

0.677 0.457 0.861 1.473 1.137 0.717 1.104

0.500 0.649 0.392 0.145 0.259 0.476 0.273

Abbreviations: MPT, maximum phonation time; HNR, harmonic-to-noise ratio; PR, phonation range; M, mean; SD, standard deviation; SDF0, standard deviation of fundamental frequency; DFx, fundamental frequency in connected speech; Qx, closed phase of vocal fold vibration.