The impact of different algorithms for ideal body weight on screening for hydroxychloroquine retinopathy in women

Figures & data

Figure 1 Distribution of heights of 269 women taking hydroxychloroquine.

Figure 2 Distribution of actual weights of 241 women taking hydroxychloroquine.

Table 1 Algorithms for ideal body weight

Name	Formula	Reference
Wolfe	Y=5.07X–203.9	^Citation2
Michaelides*	Y=3.78X–129.9	^Citation8
Metropolitan Life Insurance small frame mean value table	Y=3X–71	^Citation9,Citation15
Metropolitan Life Insurance large frame mean value table	Y=3.3X–68.9	^Citation9,Citation15
NHLBI table	Y=4.28X–134.32	^Citation10
Bergholz	Y=2.16X–0.85	^Citation16
WalvickŦ	Y=3.5X–96	^Citation7

Notes: Y, ideal body weight in pounds. X, height in inches.

* This formula depends on actual body weight at the specified height, which was taken as the mean value for patients of that height taking hydroxychloroquine in the authors’ series.

Ŧ This formula assumes that at a height of 60 inches, the ideal body weight was 114 pounds, which is the midpoint of the values of all the other algorithms. The formulas apply across a range of heights from 60 to 74 inches. When an algorithm was given as a table in the reference, the least squares best fit line to the tabulated data was used as the formula.

Abbreviation: NHLBI, National Heart Lung and Blood Institute.

Figure 3 Graphs of ideal body weight versus height for seven algorithms used in ophthalmology publications concerning screening for hydroxychloroquine retinopathy.

Abbreviation: NHLBI, National Heart Lung and Blood Institute.

Table 2 Data on different algorithms used by ophthalmologists to determine ideal body weight in screening for hydroxychloroquine retinopathy

IBW algorithm	Height (inches)																	Threshold height (inches)	% toxic at 400 mg/d	% with ABW < IBW
	60	61	62	63	64	65	66	67	68	69	70	71	72	73	74	75	76
Wolfe^Citation2	100	105	110	115	120	125	130	135	140	145	150	155	160	165	170	175	180	67	80	10
Met Life women, small frame, mean^Citation15	109	112	115	118	121	124	127	130	133	136	139	142	145	148	151	154	157	69	94	10
Met Life women, large frame, mean^Citation15	130	133	136	139	143	148	150	153	157	160	163	166	169	172	175	178	181	62	16	31
NHLBI table^Citation10	123	127	131	135	140	144	148	153	158	162	167	172	177	182	186	192	197	63	29	27
Bergholz^Citation16	129	131	133	135	137	139	142	144	146	148	150	152	155	157	159	161	163	63	29	27
Michaelides^Citation8	98	101	105	108	112	116	119	123	127	131	135	138	142	146	150	154	158	70	98	5
Walvick^Citation7	114	118	121	125	128	132	135	139	142	146	149	153	156	160	163	167	170	66	70	16

Notes: Values given are ideal body weights in pounds corresponding to the algorithm of that row and the height of that column. Threshold height, the height at which 400 mg/d hydroxychloroquine exceeds 6.5 mg/kg/d for the ideal body weight algorithm represented on the row being examined. % toxic at 400 mg/d, the percentage of patients below the threshold height based on the sample of patients studied. % with ABW < IBW, the percentage of patients in whom the actual body weight falls below the ideal body weight based on the sample of patients studied.

Abbreviations: ABW, actual body weight; IBW, ideal body weight; Met Life, Metropolitan Life Insurance table for women; NHLBI, National Heart Lung and Blood Institute.

Table 3 Data on different algorithms used by ophthalmologists to determine ideal body weight in screening for hydroxychloroquine retinopathy

IBW algorithm	Height (cm)																	Threshold height (cm)	% toxic at 400 mg/d	% with ABW < IBW
	152	155	157	160	163	165	168	170	173	175	178	180	183	185	188	191	193
Wolfe^Citation2	45.5	47.7	50.0	52.3	54.5	56.8	59.1	61.4	63.6	65.9	68.2	70.5	72.7	75.0	77.3	79.5	81.8	170	80	10
Met Life women, small frame, mean^Citation15	49.5	50.9	52.3	53.6	55.0	56.4	57.7	59.1	60.5	61.8	63.2	64.5	65.9	67.3	68.6	70.0	71.4	175	94	10
Met Life women, large frame, mean^Citation15	59.1	60.5	61.8	63.2	65.0	67.3	68.2	69.5	71.4	72.7	74.1	75.5	76.8	78.2	79.5	80.9	82.3	157	16	31
NHLBI table^Citation10	55.9	57.7	59.5	61.4	63.6	65.5	67.3	69.5	71.8	73.6	75.9	78.2	80.5	82.7	84.5	87.3	89.5	160	29	27
Bergholz^Citation16	58.6	59.5	60.5	61.4	62.3	63.2	64.5	65.5	66.4	67.3	68.2	69.1	70.5	71.4	72.3	73.2	74.1	160	29	27
Michaelides^Citation8	44.5	45.9	47.7	49.1	50.9	52.7	54.1	55.9	57.7	59.5	61.4	62.7	64.5	66.4	68.2	70.0	71.8	178	98	5
Walvick^Citation7	51.8	53.6	55.0	56.8	58.2	60.0	61.4	63.2	64.5	66.4	67.7	69.5	70.9	72.7	74.1	75.9	77.3	168	70	16

Notes: Values given are ideal body weights in kilograms corresponding to the algorithm of that row and the height of that column. Threshold height, the height at which 400 mg/d hydroxychloroquine exceeds 6.5 mg/kg/d for the ideal body weight algorithm represented on the row being examined. % toxic at 400 mg/d, the percentage of patients below the threshold height based on the sample of patients studied. % with ABW < IBW, the percentage of patients in whom the actual body weight falls below the ideal body weight based on the sample of patients studied.

Abbreviations: ABW, actual body weight; IBW, ideal body weight; Met Life, Metropolitan Life Insurance table for women; NHLBI, National Heart Lung and Blood Institute.

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