Cochrane · intervention · CD010470

Interventions for managing taste disturbances

Kumbargere Nagraj, S, George, RP, Shetty, N, et al. · Cochrane Database of Systematic Reviews · 2017 · Cochrane Library

Oral Health Oral medicine and oral cancer3 versionsAMSTAR 2: not assessed

Full textEvery question was extracted from the full review (methods and results), not only its Summary of Findings table.

Questions

current version

GRADE rated

No studies

Included studies

as reported

No studies 3 · 20%Ungraded 5 · 33.3%Very low 7 · 46.7%Low 0 · 0%Moderate 0 · 0%High 0 · 0%

Ungraded means an effect was reported without a GRADE rating; it is not a gap. No studies means the review found nothing to answer the question. The six categories are a display order, not a score.

Review question

Element	Planned (methods)	Found (results)
Population	Patients with taste disorders diagnosed clinically as dysgeusia, parageusia, ageusia, hypogeusia or phantogeusia regardless of age, gender, race, profession or residential location. Exclusions: demolitive surgery of tongue/palate/oropharynx; oral lesions (ulcers, stomatitis, candidiasis, necrosis); cerebral lesions or surgical damage to the nervous system; endocrinal/neurological disorders affecting taste or smell; drugs affecting taste perception (e.g. chemotherapy); treatment affecting salivary function (e.g. radiotherapy); hyposalivation	581 participants across 10 trials (566 in the quantitative analyses); taste disorders that were idiopathic, zinc-deficiency-induced, or secondary to chronic renal failure; eight adult trials and two paediatric trials; age range 0.5 to 83 years; sample sizes 15 to 219
Intervention	Any intervention (pharmacological or non-pharmacological) versus placebo or no treatment; any direct comparison between two active interventions (e.g. drug A vs drug B, or two doses of the same drug); all routes of administration or modes of application	Zinc sulphate (n=3); Zinc acetate (n=2); Polaprezinc (n=2); Zinc picolinate (n=1); Zinc gluconate (n=1); Acupuncture (n=1)
Comparison	Placebo; no treatment; another active intervention (direct comparison)	Placebo (n=9); Sham acupuncture (n=1)
Outcomes	Primary: taste acuity improvement to at least one quality of taste by subjective/objective assessment scales; taste discrimination improvement. Secondary: adverse events related to the interventions; health-related quality of life	Taste acuity improvement - patient-reported (n=119); Taste acuity improvement - objective continuous (n=366); Taste acuity improvement - objective continuous taste detection (n=14); Taste acuity improvement - objective continuous taste recognition (n=14); Taste acuity improvement - objective continuous individual taste sensations (n=22); Taste acuity improvement - objective dichotomous, idiopathic/zinc-deficient (n=292); Taste acuity improvement - objective dichotomous, chronic renal failure (n=24); Adverse events (n=335); Taste discrimination - zinc (Matson 2003, not analysable); Taste discrimination - acupuncture (n=37); Health-related quality of life (narrative)
Study designs	Parallel and cross-over randomised controlled trials (RCTs), pharmacological or non-pharmacological; quasi-RCTs excluded	Parallel RCTs (n=8); Cross-over RCTs (n=2)
Timing	Not specified	Zinc supplementation trials mean ~3 months (adverse events follow-up 12 to 18 weeks; cross-over trial 6 months); acupuncture trial eight weeks

Search date: 2017-07. Databases: Cochrane Oral Health's Trials Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE Ovid; Embase Ovid; CINAHL EBSCO; AMED Ovid; US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov); WHO International Clinical Trials Registry Platform (ICTRP);…

Questions and results

Current version only

Zinc supplements (zinc sulphate, zinc gluconate, zinc picolinate, zinc acetate, or polaprezinc) vs Placebo

Population: Patients with taste disturbances (dysgeusia/hypogeusia; idiopathic, zinc-deficient, or secondary to chronic renal failure)

CD010470.PUB3 (current) · 10 questions

Outcome	Effect	Evidence	Status / GRADE
Taste acuity improvement - objective outcome (continuous) - taste detection (cross-over trial) 6 months · Children with chronic renal failure same question in other reviews	MD 2.50 [0.93, 4.07] Mean taste detection 7.5 (placebo) vs MD 2.50 higher	1 study · 14 participants	Very low Downgraded: risk of bias, imprecision, publication bias
Health-related quality of life same question in other reviews	Results (health-related quality of life): None of the studies reported data on health-related quality of life. Heckmann 2005 (zinc) reported that signs of depression were less severe (Beck Depression Inventory P<0.05;…	1 study	Ungraded
Taste acuity improvement - patient-reported outcome Mean 3 months · Zinc-deficient/idiopathic taste disorder same question in other reviews	RR 1.40 [0.94, 2.09] 407 per 1000 (study population) vs 569 per 1000	2 studies · 119 participants	Very low Downgraded: risk of bias, imprecision, publication bias
Taste acuity improvement - objective outcome (continuous) - individual taste sensations Chronic renal failure same question in other reviews	Results (Mahajan 1980, chronic renal failure; Analysis 1.3): mean difference by taste sensation - salt MD 285 (95% CI 238.75 to 331.25); sweet MD 190 (142.36 to 237.64); sour MD 10 (-16.43 to 36.43); bitter MD 2.40…	1 study · 22 participants	Ungraded
Taste discrimination improvement same question in other reviews	Results: Matson 2003 used zinc sulphate for testing taste discrimination (sip and spit method); the trial did not report the details of the placebo group and thus the results could not be meta-analysed. Not GRADE-rated.	1 study	Ungraded
Taste acuity improvement - objective outcome (continuous) - taste recognition (cross-over trial) 6 months · Children with chronic renal failure same question in other reviews	MD 3.00 [0.66, 5.34] Mean taste recognition 16 (placebo) vs MD 3.00 higher	1 study · 14 participants	Very low Downgraded: risk of bias, imprecision, publication bias
Taste acuity improvement - objective outcome (dichotomous) - chronic renal failure Chronic renal failure same question in other reviews	RR 25 [1.65, 379.57]	1 study · 24 participants	Ungraded
Taste acuity improvement - objective outcome (continuous data) Mean 3 months · Idiopathic dysgeusia same question in other reviews	SMD 0.44 [0.23, 0.65]	3 studies · 366 participants	Very low Downgraded: risk of bias, imprecision, publication bias
Adverse events 12 to 18 weeks same question in other reviews	RR 5.20 [0.90, 30.19] 6 per 1000 vs 31 per 1000	3 studies · 335 participants	Very low Downgraded: risk of bias, imprecision, publication bias
Taste acuity improvement - objective outcome (dichotomous data) Mean 3 months · Idiopathic/zinc-deficient taste disorder same question in other reviews	RR 1.42 [1.09, 1.84] 435 per 1000 (study population) vs 618 per 1000	2 studies · 292 participants	Very low Downgraded: risk of bias, imprecision, publication bias

Acupuncture vs Sham control (deactivated laser sham acupuncture)

Population: Patients with idiopathic dysgeusia and hypogeusia

CD010470.PUB3 (current) · 4 questions

Outcome	Effect	Evidence	Status / GRADE
Taste discrimination improvement 8 weeks same question in other reviews	MD 2.80 [-1.18, 6.78] Mean taste discrimination 14.7 (sham) vs MD 2.80 higher	1 study · 37 participants	Very low Downgraded: risk of bias, imprecision
Health-related quality of life same question in other reviews	Results (health-related quality of life): Brandt 2008 assessed HRQoL in dysgeusia patients and reported significant improvement in psychological symptoms in the acupuncture group and increased quality of life in both…	1 study	Ungraded
Adverse events same question in other reviews	Results: The acupuncture trial (Brandt 2008) did not give any data on adverse events in either group.	0 studies	No studies
Taste acuity improvement same question in other reviews	Results: There were no data on taste acuity improvement in the included acupuncture trial (Brandt 2008).	0 studies	No studies

Zinc supplements vs Acupuncture

Population: Patients with taste disturbances (dysgeusia/hypogeusia; idiopathic, zinc-deficient, or secondary to chronic renal failure)

CD010470.PUB3 (current) · 1 question

Outcome	Effect	Evidence	Status / GRADE
Outcome NR same question in other reviews	Authors' conclusions: We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.	0 studies	No studies

Zinc supplements (zinc sulphate, zinc gluconate, zinc picolinate, zinc acetate, or polaprezinc) vs Placebo

Population: Patients with taste disturbances (dysgeusia/hypogeusia; idiopathic, zinc-deficient, or secondary to chronic renal failure)

CD010470.PUB2 · 9 questions

Outcome	Effect	Evidence	Status / GRADE
Adverse events Mean 3 months	RR 6.21 [1.12, 34.37] 1 per 1000 vs 6 per 1000	3 studies · 335 participants	Low
Taste acuity improvement - objective outcome (dichotomous) - chronic renal failure Chronic renal failure	RR 25 [1.65, 379.57]	1 study · 24 participants	Ungraded
Health-related quality of life	Results (health-related quality of life): Heckmann 2005 (zinc) reported that signs of depression in the zinc group were less severe (Beck Depression Inventory P<0.05; mood scale P<0.05), independent of serum/saliva…	1 study	Ungraded
Taste acuity improvement - objective outcome (continuous) - individual taste sensations Chronic renal failure	Results (Mahajan 1980, chronic renal failure): taste acuity described as improvement for each individual taste quality; salt, sugar and bitter taste acuity (detection and recognition) significantly improved in the…	1 study · 22 participants	Ungraded
Taste acuity improvement - objective outcome (continuous data) Mean 3 months · Idiopathic dysgeusia	SMD 0.44 [0.23, 0.65]	3 studies · 366 participants	Moderate Downgraded: publication bias
Taste acuity improvement - patient-reported outcome Mean 3 months · Zinc-deficient/idiopathic taste disorder	RR 1.45 [1.0, 2.10] 407 per 1000 (study population) vs 590 per 1000	2 studies · 119 participants	Very low Downgraded: risk of bias, imprecision, publication bias
Taste acuity improvement - objective outcome (dichotomous data) Mean 3 months · Idiopathic/zinc-deficient taste disorder	RR 1.7 [1.2, 2.01] 444 per 1000 (study population) vs 756 per 1000	1 study · 73 participants	Low Downgraded: risk of bias, publication bias
Taste discrimination improvement	Results: None of the trials comparing zinc to placebo tested for any improvement in taste discrimination.	0 studies	No studies
Taste acuity improvement - objective outcome (continuous) - taste recognition (cross-over trial) Children with chronic renal failure	SMD 1.26 [0.07, 2.44]	1 study · 14 participants	Very low Downgraded: risk of bias, imprecision, inconsistency

Acupuncture vs Sham control (deactivated laser sham acupuncture)

Population: Patients with idiopathic dysgeusia and hypogeusia

CD010470.PUB2 · 4 questions

Outcome	Effect	Evidence	Status / GRADE
Adverse events	Results: The acupuncture trial (Brandt 2008) did not give any data on adverse events in either group.	0 studies	No studies
Taste acuity improvement	Overall completeness: only one acupuncture trial (Brandt 2008) was included and it tested taste discrimination only; no data on taste acuity improvement for acupuncture.	0 studies	No studies
Taste discrimination improvement 8 weeks	MD 2.80 [-1.18, 6.78]	1 study · 37 participants	Low Downgraded: risk of bias, imprecision
Health-related quality of life	Results (health-related quality of life): Brandt 2008 reported significant improvement in the psychological symptoms in the intervention (acupuncture) group. Not meta-analysed; not GRADE-rated.	1 study	Ungraded

Zinc supplements vs Acupuncture

Population: Patients with taste disturbances (dysgeusia/hypogeusia; idiopathic, zinc-deficient, or secondary to chronic renal failure)

CD010470.PUB2 · 1 question

Outcome	Effect	Evidence	Status / GRADE
Outcome NR	Authors' conclusions: We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.	0 studies	No studies

Any pharmacological agent (including alternative medicine) vs Placebo or no treatment

Population: Patients with taste disorders (clinically diagnosed dysgeusia, parageusia, ageusia or hypogeusia), any age, sex or setting

CD010470 · 1 question

Outcome	Effect	Evidence	Status / GRADE
Outcome NR	Protocol (published 30 April 2013); no studies searched or included. Planned comparison: any pharmacological agent (including alternative medicine) versus placebo or no treatment. Planned outcomes: taste acuity…	0 studies	No studies

Any non-pharmacological method vs Placebo or no treatment (control)

Population: Patients with taste disorders (clinically diagnosed dysgeusia, parageusia, ageusia or hypogeusia), any age, sex or setting

CD010470 · 1 question

Outcome	Effect	Evidence	Status / GRADE
Outcome NR	Protocol (published 30 April 2013); no studies searched or included. Planned comparison: any non-pharmacological method versus placebo or no treatment (control). Planned outcomes: taste acuity improvement; taste…	0 studies	No studies

Active intervention A (e.g. drug A or dose X) vs Another active intervention (e.g. drug B or dose Y)

Population: Patients with taste disorders (clinically diagnosed dysgeusia, parageusia, ageusia or hypogeusia), any age, sex or setting

CD010470 · 1 question

Outcome	Effect	Evidence	Status / GRADE
Outcome NR	Protocol (published 30 April 2013); no studies searched or included. Planned comparison: direct head-to-head between two active interventions (drug A versus drug B, or two doses of the same drug).	0 studies	No studies