Anosmia, COVID-19, Hyposmia, Olfactory Disorder, Parosmia
Conditions
Brief summary
This study will investigate the efficacy of oral gabapentin in olfactory improvement following Covid-19- associated olfactory dysfunction. This is a randomized, double-blinded, placebo-controlled trial.
Detailed description
The drug will be given over a maximum 14 weeks with up to four weeks titrating up, eight weeks maintaining highest tolerable dose, and up to two weeks tapering down. Change in olfactory function from baseline to completion of 8-week fixed-dose period will be compared between the two study groups. Follow-up assessments will be conducted for both groups 4 weeks after completion of taper down.
Interventions
DRUGGabapentin gelatin capsules 300mg
Gabapentin is an anti-epileptic also used for nerve pain. This study will investigate the efficacy of gabapentin for olfactory nerve recovery and improvement in post-Covid-19 olfactory dysfunction.
DRUGPlacebo
lactose monohydrate NF
Sponsors
Washington University School of Medicine
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Masking description
double-blinded, both participants and investigators will be blinded. Intervention will be packaged in blinded fashion by pharmacist before being shipped to participants by research assistant
Intervention model description
Double-blinded, randomized, placebo-controlled trial
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Men and women between the ages of 18 and 65 years * Residing within the states of Missouri or Illinois * Clinically diagnosed or subjective olfactory dysfunction (anosmia, hyposmia, or parosmia) of 3 months duration or longer diagnosed within 2 weeks of Covid-19 infection * UPSIT score consistent with diminished olfactory function (score ≤ 33 in men and ≤ 34 in women). * Willing to respond daily to study surveys, preferably through smartphone with unlimited texting plan * In possession of ALL 7 household items: soap, burnt candle, peanut butter, herb, garlic, lemon, and coffee
Exclusion criteria
* Clinically diagnosed olfactory dysfunction secondary to genetic abnormalities or congenital dysfunction, trauma, non-Covid-19 viral infection, nasal polyps, neurodegenerative disorders * Current use of: azelastine, bromperidol, orophenadrine, oxomemazine, kratom, paraldehyde, or thalidomide * History of addiction to alcohol, cocaine, or opioids * Impaired renal function, myasthenia gravis, or myoclonus * Severe allergy to peanuts * Pregnancy or attempting pregnancy during study participation * Inability to participate in virtual trial due to lack of access to the internet or unlimited text messaging; inability to comprehend or use English language * Availability less than 6 months from time of enrollment * Residency in states other than Missouri or Illinois.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Clinical Global Impression of Improvement Scale (CGI-I) | After the 8 week FD phase and four week post-tapper | The primary outcome measure was the treatment response rate following the 8-week FD phase as determined by the CGI-I. The CGI-I is a modified 7-point Likert scale of -perceived change. Response options include: (1) much better, (2) somewhat better, (3) slightly better), (4) neither better nor worse, (5) slightly worse, (6) somewhat worse, (7) much worse. The response rate was defined as the number of participants self-reporting at least slightly better divided by the number of participants in each treatment group. Th |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| University of Pennsylvania Smell Identification Test (UPSIT) | Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period | Forty different odors are presented in this test. Scoring: Forced choice of 4 responses to identify each smell. Anosmia: score 6-18; severe microsmia: score 19-25, moderate microsmia: 26-30 in women and 26-29 in men; mild microsmia: 31-34 in women and 30-33 in men; and normosmia: score \> 34 in women and \>33 in men. The total UPSIT score can range from 0 to 40 and scores. The MCID in UPSIT score is 4. Scores are interpreted as the level of absolute smell function (i.e., normosmia, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia), using the age- and sex-related normative classification system described in the UPSIT manual (Table 1) |
| Olfactory Dysfunction Outcomes Rating (ODOR) | Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period | The ODOR questionnaire is a validated 28-item patient-reported outcome measure which assesses the physical, functional, and emotional consequences of OD. The ODOR is a 28-item instrument with each item scored as either no difficulty or very rarely bothered (0) to complete difficulty or very frequently bothered (4) with a total instrument score range of 0 to 112 points. Higher scores indicate higher degree of dysfunction and limitation. the MCID is 15 points. |
| NASAL-7 | Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period | NASAL-7 is a simple diagnostic tool for olfactory dysfunction that is based on commonly found household items and can be used by adults who suspect olfactory dysfunction. The NASAL-7 was developed by Dr. Piccirillo and colleagues in the Clinical Outcomes Research Office. The NASAL-7, contains 7 household items with each item scored as 0 for 'Cannot Smell', 1 for 'Smells Less Strong/Different Than Normal', and 2 for 'Smells Normal', for a total possible score ranging from 0-14. The following four categories of olfactory function were defined based on NASAL-7 score: anosmia (score 0-4), severe dysfunction (score 5-7), mild dysfunction (score 8-10), and normosmia (score 11-14). |
| CGI-Severity of Smell | 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase | CGI-Severity. The CGI-Severity scale ranges from 1 to 7, where 1 is normal function and 7 is complete anosmia. This assessment will provide subjective data on patients' baseline olfactory function prior to beginning the trial, after 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase |
| CGI-S of Parosmia | 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase | Clinical Global Impression-Severity Scale for Parosmics (CGI-P). The CGI-P Scale is a global rating of parosmia and the single global rating ranges from 1-5, where 1 is No Distortion, 2 is Mild Distortion, 3 is Moderate Distortion, 4 is Mostly Distorted, and 5 is Complete Distortion. The response on the CGI-P will provide information on the patient's perceived severity of the distortion of their smell. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Gabapentin This arm will be given the active treatment, oral Letco (gabapentin) gelatin capsules of 300mg each.
Up to the first four weeks will be a titration period (week 1 300mg TID, week 2 600mg TID, week 3 900mg TID, week 4 1,200mg TID) as tolerated. If intolerable adverse reactions occur, the dosage will be decreased to prior tolerable dose (e.g., if 900mg TID is intolerable, dose will be decreased to 600mg TID).
The following eight weeks will be fixed dose, the highest tolerable dose from the titration period.
Up to two weeks will be a taper down tailored to the maximum dose the participant reached during the titration and fixed periods.
A maximum 14 weeks will mark the end of active treatment. Follow-up assessments will be conducted 4 weeks after completion of the taper-down period.
Gabapentin gelatin capsules 300mg: Gabapentin is an anti-epileptic also used for nerve pain. This study will investigate the efficacy of gabapentin for olfactory nerve recovery and improvement in post-Covid-19 olfactory dysfunction. | 34 |
| Placebo Placebo gelatin capsules that look, smell, and taste like gabapentin capsules will be given to the placebo arm.
To preserve double-blinding of the study, subjects will receive one capsule TID the first week, the second week two capsules TID, the third week three capsules TID, and fourth week four capsules TID as tolerated. If intolerable, the dose will be decreased to prior tolerable dose.
The next eight weeks will be a fixed amount of placebo based on the highest tolerable amount from the titration period.
Subjects will then taper-down placebo to imitate the gabapentin arm for maximum two weeks based on highest dose achieved during study.
4 weeks after completion of taper-down, follow-up assessments will be conducted.
Placebo: lactose monohydrate NF | 34 |
| Total | 68 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Adverse Event | 1 | 4 |
| Overall Study | Concern for adverse effects | 0 | 4 |
| Overall Study | Lost to Follow-up | 4 | 7 |
| Overall Study | Medication schedule | 1 | 0 |
| Overall Study | PI withdrawal | 1 | 2 |
| Overall Study | Withdrew due to adverse effect | 1 | 0 |
Baseline characteristics
| Characteristic | Total | Placebo | Gabapentin |
|---|---|---|---|
| Age, Continuous | 43 years STANDARD_DEVIATION 13.5 | 44 years STANDARD_DEVIATION 15.5 | 42 years STANDARD_DEVIATION 10.6 |
| CGI-S of parosmia Complete distortion | 18 Participants | 9 Participants | 9 Participants |
| CGI-S of parosmia Mild distortion | 4 Participants | 4 Participants | 0 Participants |
| CGI-S of parosmia Moderate distortion | 14 Participants | 9 Participants | 5 Participants |
| CGI-S of parosmia Mostly distorted | 23 Participants | 10 Participants | 13 Participants |
| CGI-S of parosmia No distortion | 2 Participants | 2 Participants | 0 Participants |
| CGI-S of smell Absent | 11 Participants | 5 Participants | 6 Participants |
| CGI-S of smell Excellent | 0 Participants | 0 Participants | 0 Participants |
| CGI-S of smell Fair | 10 Participants | 7 Participants | 3 Participants |
| CGI-S of smell Good | 2 Participants | 1 Participants | 1 Participants |
| CGI-S of smell Poor | 37 Participants | 20 Participants | 17 Participants |
| CGI-S of smell Very good | 1 Participants | 1 Participants | 0 Participants |
| NASAL-7 categories Anosmia (0-4) | 20 Participants | 11 Participants | 9 Participants |
| NASAL-7 categories Mild dysfunction (8-10) | 9 Participants | 5 Participants | 4 Participants |
| NASAL-7 categories Normosmia (11-14) | 4 Participants | 2 Participants | 2 Participants |
| NASAL-7 categories Severe dysfunction (5-7) | 28 Participants | 16 Participants | 12 Participants |
| Olfactory Dysfunction Outcomes Rating (ODOR) | 56 score on a scale (0-112) | 54.5 score on a scale (0-112) | 56 score on a scale (0-112) |
| Race/Ethnicity, Customized Black / African American | 2 Participants | 0 Participants | 2 Participants |
| Race/Ethnicity, Customized Hispanic | 1 Participants | 1 Participants | 0 Participants |
| Race/Ethnicity, Customized Other | 2 Participants | 0 Participants | 2 Participants |
| Race/Ethnicity, Customized White | 56 Participants | 33 Participants | 23 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 2 Participants | 0 Participants | 2 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 3 Participants | 1 Participants | 2 Participants |
| Race (NIH/OMB) White | 56 Participants | 33 Participants | 23 Participants |
| Region of Enrollment United States | 68 participants | 34 participants | 34 participants |
| Sex: Female, Male Female | 51 Participants | 25 Participants | 26 Participants |
| Sex: Female, Male Male | 17 Participants | 9 Participants | 8 Participants |
| University of Pennsylvania Smell Identification Test (UPSIT) | 25.0 score on a scale (0-40) | 25.5 score on a scale (0-40) | 24.5 score on a scale (0-40) |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 18 | 0 / 26 |
| other Total, other adverse events | 10 / 18 | 11 / 26 |
| serious Total, serious adverse events | 0 / 18 | 0 / 26 |
Outcome results
Primary
Clinical Global Impression of Improvement Scale (CGI-I)
The primary outcome measure was the treatment response rate following the 8-week FD phase as determined by the CGI-I. The CGI-I is a modified 7-point Likert scale of -perceived change. Response options include: (1) much better, (2) somewhat better, (3) slightly better), (4) neither better nor worse, (5) slightly worse, (6) somewhat worse, (7) much worse. The response rate was defined as the number of participants self-reporting at least slightly better divided by the number of participants in each treatment group. Th
Time frame: After the 8 week FD phase and four week post-tapper
Population: 26 participants in the placebo group completed the treatment, but 25 participants completed the posttaper survey.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Gabapentin | Clinical Global Impression of Improvement Scale (CGI-I) | Fixed Dose Period | 8 Participants |
| Gabapentin | Clinical Global Impression of Improvement Scale (CGI-I) | 4 week post tapper | 7 Participants |
| Placebo | Clinical Global Impression of Improvement Scale (CGI-I) | Fixed Dose Period | 20 Participants |
| Placebo | Clinical Global Impression of Improvement Scale (CGI-I) | 4 week post tapper | 12 Participants |
Secondary
CGI-Severity of Smell
CGI-Severity. The CGI-Severity scale ranges from 1 to 7, where 1 is normal function and 7 is complete anosmia. This assessment will provide subjective data on patients' baseline olfactory function prior to beginning the trial, after 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
Time frame: 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
Population: 26 participants in placebo group completed treatment, but 25 participants completed the posttaper survey. 18 participants in the gabapentin group completed treatment, but 16 participants completed the posttaper survey.
| Arm | Measure | Group | Category | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|---|
| Gabapentin | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Absent | 4 Participants |
| Gabapentin | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Poor | 12 Participants |
| Gabapentin | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Fair | 1 Participants |
| Gabapentin | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Good | 1 Participants |
| Gabapentin | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Very good | 0 Participants |
| Gabapentin | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Excellent | 0 Participants |
| Gabapentin | CGI-Severity of Smell | Fixed Dose | Absent | 3 Participants |
| Gabapentin | CGI-Severity of Smell | Fixed Dose | Poor | 4 Participants |
| Gabapentin | CGI-Severity of Smell | Fixed Dose | Fair | 8 Participants |
| Gabapentin | CGI-Severity of Smell | Fixed Dose | Good | 3 Participants |
| Gabapentin | CGI-Severity of Smell | Fixed Dose | Very good | 0 Participants |
| Gabapentin | CGI-Severity of Smell | Fixed Dose | Excellent | 0 Participants |
| Gabapentin | CGI-Severity of Smell | Post taper | Absent | 2 Participants |
| Gabapentin | CGI-Severity of Smell | Post taper | Poor | 7 Participants |
| Gabapentin | CGI-Severity of Smell | Post taper | Fair | 5 Participants |
| Gabapentin | CGI-Severity of Smell | Post taper | Good | 2 Participants |
| Gabapentin | CGI-Severity of Smell | Post taper | Very good | 0 Participants |
| Gabapentin | CGI-Severity of Smell | Post taper | Excellent | 0 Participants |
| Placebo | CGI-Severity of Smell | Post taper | Poor | 13 Participants |
| Placebo | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Absent | 4 Participants |
| Placebo | CGI-Severity of Smell | Fixed Dose | Good | 3 Participants |
| Placebo | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Poor | 16 Participants |
| Placebo | CGI-Severity of Smell | Post taper | Excellent | 0 Participants |
| Placebo | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Fair | 4 Participants |
| Placebo | CGI-Severity of Smell | Fixed Dose | Very good | 1 Participants |
| Placebo | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Good | 1 Participants |
| Placebo | CGI-Severity of Smell | Post taper | Fair | 6 Participants |
| Placebo | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Very good | 1 Participants |
| Placebo | CGI-Severity of Smell | Fixed Dose | Excellent | 0 Participants |
| Placebo | CGI-Severity of Smell | Assessments of the Secondary Outcome Measures of Study Groups: Baseline | Excellent | 0 Participants |
| Placebo | CGI-Severity of Smell | Post taper | Very good | 1 Participants |
| Placebo | CGI-Severity of Smell | Fixed Dose | Absent | 5 Participants |
| Placebo | CGI-Severity of Smell | Post taper | Absent | 3 Participants |
| Placebo | CGI-Severity of Smell | Fixed Dose | Poor | 13 Participants |
| Placebo | CGI-Severity of Smell | Post taper | Good | 2 Participants |
| Placebo | CGI-Severity of Smell | Fixed Dose | Fair | 4 Participants |
Secondary
CGI-S of Parosmia
Clinical Global Impression-Severity Scale for Parosmics (CGI-P). The CGI-P Scale is a global rating of parosmia and the single global rating ranges from 1-5, where 1 is No Distortion, 2 is Mild Distortion, 3 is Moderate Distortion, 4 is Mostly Distorted, and 5 is Complete Distortion. The response on the CGI-P will provide information on the patient's perceived severity of the distortion of their smell.
Time frame: 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
Population: 26 participants in placebo group completed treatment, but 25 participants completed the posttaper survey. 18 participants in the gabapentin group completed treatment, but 16 participants completed the posttaper survey.
| Arm | Measure | Group | Category | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|---|
| Gabapentin | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | No Distortion | 0 Participants |
| Gabapentin | CGI-S of Parosmia | Fixed Dose | Mild Distortion | 5 Participants |
| Gabapentin | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Mostly Distorted | 9 Participants |
| Gabapentin | CGI-S of Parosmia | Fixed Dose | No Distortion | 1 Participants |
| Gabapentin | CGI-S of Parosmia | Fixed Dose | Complete Distortion | 2 Participants |
| Gabapentin | CGI-S of Parosmia | Post tapper | Complete Distortion | 2 Participants |
| Gabapentin | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Mild Distortion | 0 Participants |
| Gabapentin | CGI-S of Parosmia | Post tapper | Mostly Distorted | 5 Participants |
| Gabapentin | CGI-S of Parosmia | Fixed Dose | Mostly Distorted | 6 Participants |
| Gabapentin | CGI-S of Parosmia | Post tapper | Moderate Distortion | 6 Participants |
| Gabapentin | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Moderate Distortion | 2 Participants |
| Gabapentin | CGI-S of Parosmia | Post tapper | Mild Distortion | 2 Participants |
| Gabapentin | CGI-S of Parosmia | Fixed Dose | Moderate Distortion | 4 Participants |
| Gabapentin | CGI-S of Parosmia | Post tapper | No Distortion | 1 Participants |
| Gabapentin | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Complete Distortion | 7 Participants |
| Placebo | CGI-S of Parosmia | Post tapper | No Distortion | 1 Participants |
| Placebo | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Complete Distortion | 6 Participants |
| Placebo | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Mostly Distorted | 8 Participants |
| Placebo | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Moderate Distortion | 7 Participants |
| Placebo | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | Mild Distortion | 4 Participants |
| Placebo | CGI-S of Parosmia | Assessments of Secondary Outcome Measures of Study Groups: Baseline | No Distortion | 1 Participants |
| Placebo | CGI-S of Parosmia | Fixed Dose | Complete Distortion | 3 Participants |
| Placebo | CGI-S of Parosmia | Fixed Dose | Mostly Distorted | 6 Participants |
| Placebo | CGI-S of Parosmia | Fixed Dose | Moderate Distortion | 9 Participants |
| Placebo | CGI-S of Parosmia | Fixed Dose | Mild Distortion | 7 Participants |
| Placebo | CGI-S of Parosmia | Fixed Dose | No Distortion | 1 Participants |
| Placebo | CGI-S of Parosmia | Post tapper | Complete Distortion | 2 Participants |
| Placebo | CGI-S of Parosmia | Post tapper | Mostly Distorted | 9 Participants |
| Placebo | CGI-S of Parosmia | Post tapper | Moderate Distortion | 9 Participants |
| Placebo | CGI-S of Parosmia | Post tapper | Mild Distortion | 4 Participants |
Secondary
NASAL-7
NASAL-7 is a simple diagnostic tool for olfactory dysfunction that is based on commonly found household items and can be used by adults who suspect olfactory dysfunction. The NASAL-7 was developed by Dr. Piccirillo and colleagues in the Clinical Outcomes Research Office. The NASAL-7, contains 7 household items with each item scored as 0 for 'Cannot Smell', 1 for 'Smells Less Strong/Different Than Normal', and 2 for 'Smells Normal', for a total possible score ranging from 0-14. The following four categories of olfactory function were defined based on NASAL-7 score: anosmia (score 0-4), severe dysfunction (score 5-7), mild dysfunction (score 8-10), and normosmia (score 11-14).
Time frame: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Population: 26 participants in placebo group completed treatment, but 25 participants completed the posttaper survey. 18 participants in the gabapentin group completed treatment, but 16 participants completed the posttaper survey.
| Arm | Measure | Group | Category | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|---|
| Gabapentin | NASAL-7 | Baseline | Anosmia (0-4) | 6 Participants |
| Gabapentin | NASAL-7 | Baseline | Severe dysfunction (5-7) | 8 Participants |
| Gabapentin | NASAL-7 | Baseline | Mild dysfunction (8-10) | 2 Participants |
| Gabapentin | NASAL-7 | Baseline | Normosmia (11-14) | 2 Participants |
| Gabapentin | NASAL-7 | Fixed Dose | Anosmia (0-4) | 4 Participants |
| Gabapentin | NASAL-7 | Fixed Dose | Severe dysfunction (5-7) | 5 Participants |
| Gabapentin | NASAL-7 | Fixed Dose | Mild dysfunction (8-10) | 4 Participants |
| Gabapentin | NASAL-7 | Fixed Dose | Normosmia (11-14) | 5 Participants |
| Gabapentin | NASAL-7 | Post taper | Anosmia (0-4) | 5 Participants |
| Gabapentin | NASAL-7 | Post taper | Severe dysfunction (5-7) | 6 Participants |
| Gabapentin | NASAL-7 | Post taper | Mild dysfunction (8-10) | 2 Participants |
| Gabapentin | NASAL-7 | Post taper | Normosmia (11-14) | 3 Participants |
| Placebo | NASAL-7 | Post taper | Mild dysfunction (8-10) | 5 Participants |
| Placebo | NASAL-7 | Baseline | Anosmia (0-4) | 10 Participants |
| Placebo | NASAL-7 | Fixed Dose | Mild dysfunction (8-10) | 6 Participants |
| Placebo | NASAL-7 | Baseline | Severe dysfunction (5-7) | 12 Participants |
| Placebo | NASAL-7 | Post taper | Severe dysfunction (5-7) | 6 Participants |
| Placebo | NASAL-7 | Baseline | Mild dysfunction (8-10) | 3 Participants |
| Placebo | NASAL-7 | Fixed Dose | Normosmia (11-14) | 4 Participants |
| Placebo | NASAL-7 | Baseline | Normosmia (11-14) | 1 Participants |
| Placebo | NASAL-7 | Post taper | Normosmia (11-14) | 7 Participants |
| Placebo | NASAL-7 | Fixed Dose | Anosmia (0-4) | 7 Participants |
| Placebo | NASAL-7 | Post taper | Anosmia (0-4) | 7 Participants |
| Placebo | NASAL-7 | Fixed Dose | Severe dysfunction (5-7) | 9 Participants |
Secondary
Olfactory Dysfunction Outcomes Rating (ODOR)
The ODOR questionnaire is a validated 28-item patient-reported outcome measure which assesses the physical, functional, and emotional consequences of OD. The ODOR is a 28-item instrument with each item scored as either no difficulty or very rarely bothered (0) to complete difficulty or very frequently bothered (4) with a total instrument score range of 0 to 112 points. Higher scores indicate higher degree of dysfunction and limitation. the MCID is 15 points.
Time frame: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Population: 26 participants in placebo group completed treatment, but 25 participants completed the posttaper survey.~18 participants in the gabapentin group completed treatment, but 16 participants completed the post-taper survey.~Each of the 28 items is scored 0 to 4. The maximum total score is 112 with higher scores representing greater quality of life impairment.~The MCID is 15.
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Gabapentin | Olfactory Dysfunction Outcomes Rating (ODOR) | Baseline | 23 score on a scale (0-112) |
| Gabapentin | Olfactory Dysfunction Outcomes Rating (ODOR) | Fixed Dose | 25.5 score on a scale (0-112) |
| Gabapentin | Olfactory Dysfunction Outcomes Rating (ODOR) | Post Taper | 25 score on a scale (0-112) |
| Placebo | Olfactory Dysfunction Outcomes Rating (ODOR) | Baseline | 54.5 score on a scale (0-112) |
| Placebo | Olfactory Dysfunction Outcomes Rating (ODOR) | Fixed Dose | 49.9 score on a scale (0-112) |
| Placebo | Olfactory Dysfunction Outcomes Rating (ODOR) | Post Taper | 45 score on a scale (0-112) |
Secondary
University of Pennsylvania Smell Identification Test (UPSIT)
Forty different odors are presented in this test. Scoring: Forced choice of 4 responses to identify each smell. Anosmia: score 6-18; severe microsmia: score 19-25, moderate microsmia: 26-30 in women and 26-29 in men; mild microsmia: 31-34 in women and 30-33 in men; and normosmia: score \> 34 in women and \>33 in men. The total UPSIT score can range from 0 to 40 and scores. The MCID in UPSIT score is 4. Scores are interpreted as the level of absolute smell function (i.e., normosmia, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia), using the age- and sex-related normative classification system described in the UPSIT manual (Table 1)
Time frame: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Population: 26 participants in placebo group completed treatment, but 25 participants completed the posttaper survey. 18 participants in the gabapentin group completed treatment, but 16 participants completed the post-taper survey.
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Gabapentin | University of Pennsylvania Smell Identification Test (UPSIT) | Baseline | 23 score on a scale (0-40) |
| Gabapentin | University of Pennsylvania Smell Identification Test (UPSIT) | Fixed Dose | 25 score on a scale (0-40) |
| Gabapentin | University of Pennsylvania Smell Identification Test (UPSIT) | Post-taper | 26 score on a scale (0-40) |
| Placebo | University of Pennsylvania Smell Identification Test (UPSIT) | Baseline | 24 score on a scale (0-40) |
| Placebo | University of Pennsylvania Smell Identification Test (UPSIT) | Fixed Dose | 25 score on a scale (0-40) |
| Placebo | University of Pennsylvania Smell Identification Test (UPSIT) | Post-taper | 25 score on a scale (0-40) |