Handling missing items in the Hospital Anxiety and Depression Scale (HADS): a simulation study

Bell, Melanie L.; Fairclough, Diane L.; Fiero, Mallorie H.; Butow, Phyllis N.

doi:10.1186/s13104-016-2284-z

BMC Research Notes

Table 3 Bias and imprecision of population means for the HADS depression subscale, and correlation with quality of life

From: Handling missing items in the Hospital Anxiety and Depression Scale (HADS): a simulation study

Method	Bias			Imprecision			Correlation with QoL^a
Method	Random	Demog	Subscale	Random	Demog	Subscale	Random	Demog	Subscale
25 % missing item, rate = p_sub = 0.5 p_item = 0.5
Subject mean	0.083	0.002	−0.061	0.037	0.033	0.047	−0.754	−0.759	−0.752
Subscale mean	0.004	−0.011	−0.024	0.046	0.051	0.071	−0.722	−0.715	−0.701
Subscale ½ mean	0.000	−0.357	−1.102	0.141	0.258	1.377	−0.756	−0.757	−0.729
Item mean	0.001	−0.360	−1.110	0.062	0.189	1.277	−0.756	−0.721	−0.717
Multiple imputation	0.016	−0.086	−0.324	0.038	0.053	0.175	−0.711	−0.744	−0.729
Multiple imputation ½	0.005	−0.382	−1.218	0.136	0.274	1.638	−0.742	−0.769	−0.732
Complete case	−0.016	−1.026	−3.168	0.348	1.347	10.162	−0.769	−0.769	−0.427
10 % missing item rate, p_sub = 0.5 p_item = 0.2
Subject mean	0.028	0.002	−0.025	0.010	0.009	0.013	−0.768	−0.769	−0.768
Subscale mean	−0.003	0.001	−0.002	0.010	0.010	0.015	−0.760	−0.768	−0.754
Subscale ½ mean	−0.000	−0.025	−0.067	0.016	0.019	0.026	−0.769	−0.768	−0.743
Item mean	−0.002	−0.123	−0.372	0.014	0.030	0.154	−0.758	−0.755	−0.743
Multiple imputation	0.005	−0.012	−0.075	0.011	0.012	0.023	−0.766	−0.765	−0.765
Multiple imputation ½	0.003	−0.033	−0.130	0.016	0.021	0.040	−0.770	−0.769	−0.746
Complete case	−0.000	−0.695	−2.122	0.201	0.699	4.720	−0.770	−0.770	−0.716
10 % missing item rate, p_sub = 0.2 p_item = 0.5
Subject mean	0.034	0.003	−0.082	0.014	0.014	0.025	−0.764	−0.767	−0.765
Subscale mean	0.000	−0.006	−0.010	0.018	0.020	0.028	−0.750	−0.747	−0.740
Subscale ½ mean	0.002	−0.134	−0.701	0.041	0.064	0.575	−0.764	−0.766	−0.730
Item mean	−0.002	−0.132	−0.702	0.022	0.041	0.514	−0.745	−0.746	−0.731
Multiple imputation	−0.005	−0.027	−0.234	0.013	0.015	0.080	−0.761	−0.761	−0.758
Multiple imputation ½	−0.000	−0.139	−0.774	0.040	0.064	0.672	−0.766	−0.769	−0.734
Complete case	−0.003	−0.285	−1.540	0.077	0.161	2.409	−0.768	−0.772	−0.666
2 % missing item rate, p_sub = 0.1 p_item = 0.2
Subject mean	0.006	−0.000	−0.023	0.002	0.002	0.003	−0.769	−0.771	−0.771
Subscale mean	−0.000	−0.000	0.001	0.002	0.002	0.003	−0.767	−0.767	−0.767
Subscale ½ mean	0.000	−0.009	−0.034	0.003	0.004	0.010	−0.768	−0.768	−0.766
Item mean	0.000	−0.029	−0.166	0.003	0.004	0.033	−0.766	−0.766	−0.767
Multiple imputation	0.001	−0.004	−0.038	0.002	0.002	0.005	−0.768	−0.769	−0.769
Multiple imputation ½	0.001	−0.01	−0.068	0.003	0.004	0.014	−0.769	−0.769	−0.768
Complete case	−0.000	−0.119	−0.679	0.026	0.043	0.500	−0.770	−0.770	−0.729

N = 52 for random, demographic dependent and subscale dependent missingness mechanisms. 1000 simulated datasets
^aCorrelation = −0.767 for original data (n = 1444)

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ISSN: 1756-0500

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