Impact of being underweight on peri-operative and post-operative outcomes of total knee or hip arthroplasty: A meta-analysis

Table 1 Search strategy

Database	Search strategy	Results
PubMed	((((“Under-weight”) OR (Low body mass index)) OR (malnourished)) AND (((("total knee arthroplasty"[All Fields]) OR ("total hip arthroplasty"[All Fields])) OR ("total joint arthroplasty"[All Fields])) OR ("total knee replacement"[All Fields]))) AND (((((mortality) OR (complications)) OR (readmissions)) OR (rehospitalization)) OR (length of hospital stay))	243
CENTRAL	#1 Underweight	25
	#2 Low body mass index
	#3 Malnourished
	#4 #1 OR #2 OR #3
	#5 MeSH descriptor: [Arthroplasty, Replacement, Knee] explode all trees
	#6 MeSH descriptor: [Arthroplasty, Replacement, Hip] explode all trees
	#7 MeSH descriptor: [Arthroplasty, Replacement] explode all trees
	#8 #5 OR #6 OR #7
	#9 #4 AND #8
EMBASE	((((“Under-weight”) OR (Low body mass index)) OR (malnourished)) AND (((("total knee arthroplasty"[All Fields]) OR ("total hip arthroplasty"[All Fields])) OR ("total joint arthroplasty"[All Fields])) OR ("total knee replacement"[All Fields]))) AND (((((mortality) OR (complications)) OR (readmissions)) OR (rehospitalization)) OR (length of hospital stay))	67
WoS	TS=(“under-weight” OR "low body mass index" OR malnourished ) AND TS=("Total knee arthroplasty" OR " Total joint arthroplasty" OR "Total hip arthroplasty") AND TS=(mortality OR complications OR rehospitalization OR readmissions OR “length of hospital stay” )	110
SCOPUS	ALL (“under-weight” OR "low body mass index" OR malnourished) AND ALL ("Total knee arthroplasty" OR " Total joint arthroplasty" OR "Total hip arthroplasty") AND ALL (mortality OR complications OR rehospitalization OR re-admissions OR “length of hospital stay”)	261

MeSH: Medical subheadings; TS: Topic; WoS: Web of science.

Table 2 Characteristics of included studies

Ref.	Type of study	Total participants	Age (mean)	Follow up time	Gender (F/M)	Treatment	Groups	Number of participants per group
Hartford et al[20], 2020	Retrospective	1774	67.08	3 mo	1078/696	THA	Underweight	13
							Normal	463
Katakam et al[18], 2021	Retrospective	4802	65.9	2 yr	2698/2104	THA and TKA	Underweight2	85
							Normal	821
Kwon et al[19], 2020	Retrospective	118	70.75	2 yr	118/0	TKA	Underweight	41
							Normal	77
Sloan et al[22], 2019	Retrospective	378775	65.7	1 mo	224912/153863	THA and TKA	Underweight	1846
							Normal	51130
Hung et al[24], 2019	Retrospective	1565	54.46	1 mo	830/735	THA	Underweight	56
							Normal	697
Sayed-Noor et al[23], 2019	Prospective	83146	69	2 yr (90 d mortality)	47210/35936	THA	Underweight	579
							Normal	25718
Woo et al[21], 2019	Retrospective	3672	78.06	1 yr	2620/1007	THA	Underweight	332
							Normal	750
Dowsey et al[27], 2018	Retrospective	172767	67.65	5 yr	104742/68024	THA and TKA	TKA + Underweight	268
							TKA + Normal	13261
							THA +Underweight	492
							THA + Normal	13226
Shohat et al[25], 2018	Retrospective	18173	61.33	3 mo	9986/8187	THA and TKA	Underweight	96
							Normal	3266
Zusmanovich et al[9], 2018	Retrospective	840	72.05	1 mo	660/180	THA	Underweight	301
							Normal	539
Mouchti et al[26], 2018	Prospective	415598	67.75	3 mo	246780/168818	THA	Underweight	3588
							Normal	86336
Manrique et al[10], 2017	Retrospective	108	69.7	3.8 yr	93/24	TKA	Underweight	27
							Normal	81
Anoushiravani et al[30], 2016	Retrospective	4864	70.54	NA	4064/800	THA and TKA	THA + Underweight1	1762
							THA + Normal	1787
							TKA + Underweight	670
							TKA + Normal	645
Husted et al[29], 2016	Prospective	13730	NR	3 mo	NR	THA and TKA	TKA + Underweight	29
							TKA + Normal	1250
							THA + Underweight	77
							THA + Normal	2396
Shaparin et al[28], 2016	Retrospective	880	61.33	1 mo	541/339	THA	Underweight	17
							Normal	168
Zhao et al[31], 2014	Prospective	236	36.5	NA	34/202	THA	Underweight	91
							Normal	145
Thornqvist et al[32], 2014	Retrospective	34744	70.6	1 mo	20438/14306	THA and TKA	Underweight	353
							Normal	9859
Zhang et al[33], 2012	Prospective	714	62.17	5-20 yr	315/399	THA	Underweight	62
							Normal	413

¹Underweight < 19.5 kg/m².

²Underweight < 20 kg/m².

Underweight < 18.5 kg/m², Normal – 18.5 – 24.9 kg/m². THA: Total hip arthroplasty; TKA: Total knee arthroplasty; NA: Not available; NR: Not reported, Ref: reference; mo: Month; yr: Year; F: Female; M: Male

Table 3 Newcastle-Ottawa Scale scores for assessing the quality of included studies

Ref.	Selection				Comparability	Outcome			Total
	Representativeness of the exposed cohort	Selection of the non-exposed cohort	Ascertainment of exposure	Demonstration that outcome of interest	Basis of the design or analysis	Assessment of outcome	Follow-up long enough for outcomes	Adequate follow up
Hartford et al[20], 2020	1	1	0	1	1	1	1	1	7
Katakam et al[18], 2021	1	1	1	1	1	1	1	1	8
Kwon et al[19], 2020	1	1	1	1	1	1	1	1	8
Sloan et al[22], 2019	1	1	0	1	1	1	1	1	7
Hung et al[24], 2019	1	1	1	1	1	1	1	1	8
Sayed-Noor et al[23], 2019	1	1	1	1	1	1	1	1	8
Woo et al[21], 2019	1	1	1	1	1	1	1	1	8
Dowsey et al[27], 2018	1	1	1	1	1	1	1	1	8
Shohat et al[25], 2018	1	1	1	1	1	1	1	1	8
Zusmanovich et al[9], 2018	1	1	1	1	2	1	1	1	9
Mouchti et al[26], 2018	1	1	1	1	1	1	1	1	8
Manrique et al[10], 2017	1	1	0	0	1	1	1	1	6
Anoushiravani et al[30], 2016	1	1	0	1	1	1	1	1	7
Husted et al[29], 2016	1	1	1	1	1	1	1	1	8
Shaparin et al[28], 2016	1	1	1	1	1	1	1	1	8
Zhao et al[31], 2014	1	1	0	1	1	1	1	1	7
Thornqvist et al[32], 2014	1	1	1	1	1	1	1	1	8
Zhang et al[33], 2012	1	1	1	1	1	1	1	1	8