The voice quality after laser surgery versus radiotherapy of T1a glottic carcinoma: systematic review and meta-analysis

Figures & data

Figure 1 Stages of the systematic review of the trials.

Abbreviation: RCT, randomized controlled trial.

Table 1 Characteristics and demographics of included studies

Reference	Year	Design	Group, n		Classification of LS, n			Classification of RT, n			Male/female, n		Mean age, years		Follow-up time, months		NOS
			LS	RT	T1a	T1b	T2	T1a	T1b	T2	LS	RT	LS	RT	LS	RT
Cragle and Brandenburg^Citation24	1993	Retrospective	11	20	11	0	0	20	0	0	n/a	n/a	n/a	n/a	≥5.0	≥5.0	7
McGuirt et al^Citation25	1994	Retrospective	11	13	11	0	0	13	0	0	11/0	13/0	n/a	n/a	≥6.0	≥6.0	7
Rydell et al^Citation26	1995	Retrospective	18	18	18	0	0	18	0	0	18/0	18/0	65.2	63.9	24.0	24.0	7
Wedman et al^Citation27	2002	Retrospective	15	9	15	0	0	9	0	0	n/a	n/a	n/a	n/a	≥24.0	≥24.0	7
Tamura et al^Citation28	2003	Retrospective	14	6	14	0	0	6	0	0	14/0	6/0	69.0	71.0	26.3	21.3	6
Krengli et al^Citation29	2004	Retrospective	30	27	30	0	0	27	0	0	29/1	26/1	67.5	69.0	62.0	60.0	7
Peeters et al^Citation30	2004	Retrospective	52	40	52	0	0	40	0	0	47/5	38/2	66.0	64.0	≥12.0	≥12.0	7
Loughran et al^Citation31	2005	Retrospective	18	18	18	0	0	18	0	0	18/0	18/0	69.4	70.3	27.6	31.4	7
Goor et al^Citation32	2007	Retrospective	54	35	54	0	0	35	0	0	49/5	30/35	67.4	63.8	24.0	24.0	7
Nunez et al^Citation33	2008	Retrospective	19	18	19	0	0	13	5	0	n/a	n/a	64.0	67.0	30.0	43.0	8
Sjogren et al^Citation15	2008	Retrospective	18	16	18	0	0	16	0	0	14/4	13/3	67.0	69.0	45.0	60.0	7
van Gogh et al^Citation34	2012	Prospective	67	39	67	0	0	39	0	0	67/0	39/0	n/a	n/a	24.0	24.0	8
Aaltonen et al^Citation16	2014	RCT	31	25	31	0	0	25	0	0	31/0	25/0	69.0	61.0	24.0	24.0	9
Kono et al^Citation14	2016	Retrospective	37	27	37	0	0	27	0	0	33/4	22/5	n/a	69.0	24.0	37.0	8

Abbreviations: LS, laser surgery; n, number of patients; n/a, not available; NOS, Newcastle–Ottawa Quality Assessment Scale; RCT, randomized controlled trial; RT, radiotherapy.

Table 2 VHI of the two treatment groups in the included studies

Reference	LS group			RT group
	n	Mean	SD	n	Mean	SD
Peeters et al^Citation30	52	12	30	40	18	26
Loughran et al^Citation31	18	22.2	24.6	18	25.4	24.7
Goor et al^Citation32	36	10.6	32	20	17.1	38.7
Nunez et al^Citation33	19	28.79	19.8	18	9.67	9.1
Kono et al^Citation14	37	29.3	4.9	27	12.6	3.2

Abbreviations: LS, laser surgery; n, number of patients; RT, radiotherapy; SD, standard deviation; VHI, Voice Handicap Index.

Table 3 Acoustic analysis of the two treatment groups in the included studies

Reference	LS group						RT group
	n	MPT	F0	AFR	Jitter	Shimmer	n	MPT	F0	AFR	Jitter	Shimmer
Cragle and Brandenburg^Citation24	11	16.00±1.00	n/a	204.00±1.0	n/a	13.14±1.00	20	17.50±1.00	n/a	142.00±1.00	n/a	14.46±1.00
McGuirt et al^Citation25	11	15.81±1.00	157.0±1.00	118.5±1.1	0.74±1.00	n/a	13	19.26±1.00	136.00±1.00	177.21±1.10	0.84±1.00	n/a
Rydell et al^Citation26	18	n/a	125.0±1.00	n/a	1.20±1.50	8.00±1.00	18	n/a	107.00±1.00	n/a	0.70±0.03	8.25±0.50
Wedman et al^Citation27	9	n/a	144.0±20.00	n/a	8.67±2.89	1.31±0.26	15	n/a	137.00±12.00	n/a	8.38±1.66	1.68±0.31
Tamura et al^Citation28	14	14.30±6.46	169.0±37.83	237±123.7	1.13±0.85	3.80±1.60	6	18.06±3.48	160.00±43.20	165.00±73.88	0.93±0.58	2.82±1.78
Krengli et al^Citation29	30	n/a	134.5±33.39	n/a	5.90±5.70	12.20±2.90	27	n/a	167.80±55.88	n/a	2.30±1.39	8.00±4.32
Nunez et al^Citation33	19	11.83±5.28	173.4±47.41	n/a	0.44±0.24	5.08±4.72	18	8.63±3.23	199.04±51.46	n/a	0.72±0.91	4.07±4.09
Sjogren et al^Citation15	18	n/a	156.0±1.83	n/a	n/a	n/a	16	n/a	145.00±2.74	n/a	n/a	n/a
van Gogh et al^Citation34	67	n/a	141±33	n/a	0.46±0.49	5.28±3.19	39	n/a	124±29	n/a	0.62±0.62	5.81±3.75
Kono et al^Citation14	37	14.5±4.2	180.6±16.6	n/a	4.13±0.63	7.45±1.06	27	18.1±4.7	167.2±11.1	n/a	1.64±0.34	3.39±0.39

Abbreviations: AFR, air flow rate; F₀, fundamental frequency; LS, laser surgery; MPT, maximum phonation time; n, number of patients; n/a, not available; RT, radiotherapy.

Figure 2 Forest plots of Voice Handicap Index (VHI).

Notes: The random-effects meta-analysis model (Mantel–Haenszel method) was used in this analysis. This is presented graphically as a black diamond, where the center of the diamond is the overall estimate and the width of the diamond is the overall confidence interval; the size of the green squares denotes the weight given to the study, with larger squares reflecting more weight.
Abbreviations: CI, confidence interval; IV, inverse variance; LS, laser surgery; RT, radiotherapy; SD, standard deviation.

Figure 3 Forest plots of acoustic analysis outcomes.

Notes: Forest plots of (A) MPT, (B) F₀, (C) Jitter, (D) Shimmer, and (E) AFR. The random-effects meta-analysis model (Mantel–Haenszel method) was used in this analysis. This is presented graphically as a black diamond, where the center of the diamond is the overall estimate and the width of the diamond is the overall confidence interval; the size of the green squares denotes the weight given to the study, with larger squares reflecting more weight.
Abbreviations: AFR, air flow rate; CI, confidence interval; F₀, fundamental frequency; IV, inverse variance; LS, laser surgery; MPT, maximum phonation time; RT, radiotherapy; SD, standard deviation.

Figure 4 Publication bias: funnel plots of F₀.

Abbreviations: F₀, fundamental frequency; MD, mean difference; SE, standard error.

Table 4 Summary statistics of pooled data comparing LS versus RT

Outcome	Number of studies	Number of cases	MD	95% CI	Heterogeneity	Test for overall effect
VHI	5	285	5.86	−5.22, 16.94	P<0.00001, I^2=96.0%	Z=1.04, P=0.30
MPT	5	176	−1.89	−3.66, −0.11	P<0.00001, I^2=86%	Z=2.08, P=0.04
F0	9	402	14.06	10.30, 17.83	P<0.00001, I^2=95%	Z=7.32, P<0.00001
AFR	3	75	21.46	−78.79, 121.72	P<0.00001, I^2=100%	Z=0.42, P=0.67
Jitter	8	368	0.73	−0.37, 1.83	P<0.00001, I^2=98%	Z=1.30, P=0.20
Shimmer	8	375	0.93	−0.81, 2.67	P<0.00001, I^2=98%	Z=1.05, P=0.29

Abbreviations: AFR, air flow rate; CI, confidence interval; F₀, fundamental frequency; LS, laser surgery; MD, mean difference; MPT, maximum phonation time; RT, radiotherapy; VHI, Voice Handicap Index.

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