Background
Context
National guidance
Existing evidence on the cost-effectiveness of screening for depression in the postnatal period
Existing evidence on the cost-effectiveness of screening for depression in the antenatal period
Aim of this study
Methods
Target population and setting
Screening strategies
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Whooley only - The Whooley questions are “During the past month, have you often been bothered by feeling down, depressed or hopeless?” and “During the past month, have you often been bothered by having little interest or pleasure in doing things?”. Answering yes to either question indicates a positive screen;
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EPDS only – The EPDS is a ten-item self-administered tool originally developed to assist in identifying possible symptoms of depression in the postnatal period. It also has adequate sensitivity and specificity to identify depressive symptoms in the antenatal period. A score of 13 or more was used to indicate a positive screen.
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Whooley followed by EPDS for those who are Whooley positive;
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No-screening (routine clinical assessment with midwives at the first antenatal appointment identifying depression via discussion and clinical judgement).
Time horizon
Model structure
Model parameters
Clinical input parameters
Parametre | Base-case probabilities | Raw data probabilities based on | 95% CI | Source | Distribution | Notes |
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SCREENING PATHWAY | ||||||
Whooley | ||||||
Whooley positive | 0.0909 | 906 | 0.085–0.097 | Howard et al., 2018a [15] | Beta | – |
Whooley negative | 0.9091 | 9057 | 0.903–0.915 | Howard et al., 2018a [15] | Beta | – |
Whooley positive - true positive | 0.4530 | 410.4 | 0.420–0.485 | Howard et al., 2018a [15] | Beta | – |
Whooley positive - false positive | 0.5470 | 495.6 | 0.515–0.580 | Howard et al., 2018a [15] | Beta | – |
Whooley negative - true negative | 0.9341 | 8460 | 0.929–0.939 | Howard et al., 2018a [15] | Beta | – |
Whooley negative - false negative | 0.0659 | 596.8 | 0.061–0.071 | Howard et al., 2018a [15] | Beta | – |
EPDS | ||||||
EPDS positive | 0.1144 | 1138 | 0.108–0.121 | Howard et al., 2018a [15] | Beta | – |
EPDS negative | 0.8856 | 8809 | 0.879–0.892 | Howard et al., 2018a [15] | Beta | – |
EPDS positive - true positive | 0.5188 | 590.6 | 0.490–0.548 | Howard et al., 2018a [15] | Beta | – |
EPDS positive - false positive | 0.4813 | 547.9 | 0.452–0.510 | Howard et al., 2018a [15] | Beta | – |
EPDS negative - true negative | 0.9534 | 8398 | 0.949–0.958 | Howard et al., 2018a [15] | Beta | – |
EPDS negative - false negative | 0.0466 | 410.3 | 0.042–0.051 | Howard et al., 2018a [15] | Beta | – |
Whooley-EPDS | ||||||
Whooley positive | 0.0895 | 890.2 | 0.084–0.095 | Howard et al., 2018a [15] | Beta | – |
Whooley negative | 0.9105 | 9057 | 0.905–0.916 | Howard et al., 2018a [15] | Beta | – |
Whooley positive, EPDS positive | 0.4114 | 366.2 | 0.379–0.444 | Howard et al., 2018a [15] | Beta | – |
Whooley positive, EPDS negative | 0.5886 | 524 | 0.556–0.621 | Howard et al., 2018a [15] | Beta | – |
Whooley positive, EPDS positive - true positive | 0.7500 | 8460 | 0.741–0.759 | Howard et al., 2018a [15] | Beta | – |
Whooley positive, EPDS positive - false positive | 0.2500 | 596.8 | 0.241–0.259 | Howard et al., 2018a [15] | Beta | – |
Whooley positive, EPDS negative - true negative | 0.7531 | 274.6 | 0.708–0.797 | Howard et al., 2018a [15] | Beta | – |
Whooley positive, EPDS negative - false negative | 0.2469 | 91.55 | 0.203–0.291 | Howard et al., 2018a [15] | Beta | – |
Whooley negative - true negative | 0.9341 | 394.6 | 0.910–0.953 | Howard et al., 2018a [15] | Beta | – |
Whooley negative - false negative | 0.0659 | 129.4 | 0.047–0.090 | Howard et al., 2018a [15] | Beta | – |
No-Screen | ||||||
No-screen positive | 0.0438 | 6 | 0.016–0.084 | Hearn et al., 1998 [28] | Beta | – |
No-screen negative | 0.9562 | 131 | 0.916–0.984 | Hearn et al., 1998 [28] | Beta | – |
No-screen positive - true positive | 0.6667 | 4 | 0.284–0.947 | Hearn et al., 1998 [28] | Beta | – |
No-screen positive - false positive | 0.3333 | 2 | 0.053–0.716 | Hearn et al., 1998 [28] | Beta | – |
No-screen negative - true negative | 0.8855 | 116 | 0.826–0.934 | Hearn et al., 1998 [28] | Beta | – |
No-screen negative - false negative | 0.1145 | 15 | 0.066–0.174 | Hearn et al., 1998 [28] | Beta | – |
TREATMENT PATHWAY | ||||||
Treatment | ||||||
Facilitated self help for mild/moderate depression | 0.7921 | 79.21 | 0.705–0.864 | Howard et al., 2018 [15] | Beta | Assuming 50% of women with moderate depression receive this treatment |
High intensity psychological therapy for moderate/severe depression | 0.2079 | 20.79 | 0.136–0.295 | Howard et al., 2018 [15] | Beta | Assuming 50% of women with moderate depression receive this treatment |
Spontaneous recovery | ||||||
Spontaneous recovery | 0.3300 | 33 | 0.242–0.425 | Dennis et al., 2009 [29] | Beta | Midpoint of spontaneous recovery rate (25–40% = 33%). |
No spontaneous recovery | 0.6700 | 67 | 0.575–0.758 | Dennis et al., 2009 [29] | Beta | One minus midpoint of spontaneous recovery rate. |
Later identification | ||||||
Identified as depressed following first antenatal appointment | 0.1025 | 10.25 | 0.050–0.166 | Kessler et al., 2002 [30] | Beta | Based on 41% of misdiagnoses identified over the following 3 years. |
Not identified as depressed following first antenatal appointment | 0.8975 | 89.75 | 0.834–0.950 | Kessler et al., 2002 [30] | Beta | One minus rate of identification. |
Response to treatment | ||||||
Respond to facilitated self help | 0.5109 | 51.09 | 0.413–0.607 | NICE 2014 [17] | Beta | One minus probability of not responding. |
No response to facilitated self help | 0.4891 | 48.91 | 0.393–0.587 | NICE 2014 [17] | Beta | |
Respond to high intensity psychological therapy | 0.6784 | 67.84 | 0.586–0.767 | NICE 2014 [17] | Beta | One minus probability of not responding. |
No response to high intensity psychological therapy | 0.3216 | 32.16 | 0.233–0.414 | NICE 2014 [17] | Beta |
Outcomes
Parameter | Values | Source | Distribution | Standard error | 95% CI |
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Utilities | |||||
Ante-natal depressed | 0.678 | Littlewood et al., 2018 [25] | Beta | 0.04 | 0.600–0.756 |
Ante-natal not depressed | 0.888 | Littlewood et al., 2018 [25] | Beta | 0.01 | 0.868–0.908 |
Post-natal depressed | 0.771 | Littlewood et al., 2018 [25] | Beta | 0.03 | 0.712–0.830 |
Post-natal not depressed | 0.907 | Littlewood et al., 2018 [25] | Beta | 0.01 | 0.887–0.927 |
QALYs (9 months) | |||||
Depressed to non-depressed | 0.6553 | Beta | 30% | 0.270–1.00 | |
Depressed to depressed | 0.5991 | Beta | 30% | 0.247–0.951 | |
Non-depressed to non-depressed | 0.7422 | Beta | 30% | 0.306–1.179 |
Resource use and unit costs
Parameter | Cost (£) | Source | Distribution | Standard error | 95% CI | Notes |
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SCREENING | ||||||
Whooley | 4.53 | Department of Health 2015/6 [42] | Gamma | Assumed to be 30% of the mean value | 1.87–7.19 | Based on 1.71 minutes to screen (Littlewood et al., 2018) [25] with a midwife costing £2.65 per minute (£53 per midwife appointment, average of 20 minutes per appointment, based on clinical opinion). |
EPDS | 9.38 | Department of Health 2015/6 [42] | Gamma | Assumed to be 30% of the mean value | 3.86–14.90 | Based on 3.54 minutes to screen (Littlewood et al., 2018) [25] with a midwife costing £2.65 per minute (£53 per midwife appointment, average of 20 minutes per appointment, based on clinical opinion). |
Whooley-EPDS | 5.37 | Department of Health 2015/6 [42] | Gamma | Assumed to be 30% of the mean value | 2.21–8.53 | Weighted cost based on the above – cost of Whooley screen for those who screen Whooley negative and cost of Whooley screen plus EPDS screen for those who screen Whooley positive, with proportions taken from the screening data in Table 1. |
No-screening | 7.95 | Department of Health 2015/6 [42] | Gamma | Assumed to be 30% of the mean value | 3.28–12.62 | Based on 3 minutes with a midwife (expert opinion that without a screening tool the midwife has a conversation about mental health of around 1–5 minutes).a |
TREATMENT | ||||||
Facilitated self-help | 759 | Radhakrishnan et al., 2013 [43] | Gamma | Assumed to be 30% of the mean value | 312.71–1205.29 | |
High-intensity psychological intervention | 3114 | Radhakrishnan et al., 2013 [43] | Gamma | Assumed to be 30% of the mean value | 1282.97–4945.03 | |
OTHER HEALTH AND SOCIAL CARE | ||||||
True positive who do not respond to treatment | 2005 | Petrou et al., 2002 [45] | Gamma | Assumed to be 30% of the mean value | 826.06–3183.94 | £2419 for women with depression over 18 months in 2000 prices inflated to 2015/16 prices (Curtis and Burns, 2018 [44]), and interpolated to 9 months. |
True positive who respond to treatment | 1680 | Petrou et al., 2002 [45] | Gamma | Assumed to be 30% of the mean value | 692.16–2667.84 | £2027 for women without depression over 18 months in 2000 prices inflated to 2015/16 prices (Curtis and Burns, 2018 [44]), and interpolated to 9 months. |
True negative | 1680 | Petrou et al., 2002 [45] | Gamma | Assumed to be 30% of the mean value | 692.16–2667.84 | £2027 for women without depression over 18 months in 2000 prices inflated to 2015/16 prices (Curtis and Burns, 2018 [44]), and interpolated to 9 months. |
False negative | 2005 | Petrou et al., 2002 [45] | Gamma | Assumed to be 30% of the mean value | 826.06–3183.94 | £2419 for women with depression over 18 months in 2000 prices inflated to 2015/16 prices (Curtis and Burns, 2018 [44]), and interpolated to 9 months. |
False positive | 1680 | Petrou et al., 2002 [45] | Gamma | Assumed to be 30% of the mean value | 692.16–2667.84 | £2027 for women without depression over 18 months in 2000 prices inflated to 2015/16 prices (Curtis and Burns, 2018 [44]), and interpolated to 9 months. |
Assumptions
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All screening tools are used with all women at the first antenatal appointment;
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Women screened by antenatal services are not already receiving treatment for depression at the point of screening and therefore all women who screen positive will be referred for treatment;
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All women screened positive for depression are referred to IAPT, irrespective of the severity of depression’; All referrals to IAPT are accepted;
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No-one who screens negative and are true negatives at the first antenatal appointment become depressed following the appointment.
Model outputs
Sensitivity analysis
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Detection in the no-screen pathway - The probabilities of the no-screen pathway were based on a study examining midwives’ ability to detect mental health problems without a screening tool [28]. However, this paper is from 1998 and reported very low rates of detection. Therefore, consistent with related models [17, 25], the probabilities associated with the no-screen pathway were replaced with those from a study on the detection of depression by GPs, and the cost of a GP contact replaced the cost of the nurse screening (as shown in Table 4) (sensitivity analysis 1a). Additionally, to challenge assumptions about costs and effectiveness of the no screening arm, we re-ran this analysis but replaced the cost of a GP contact with £0 (sensitivity analysis 1b).
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Treatment pathways – The basecase analysis assumed 50% of people with moderate depression would receive self-help and the other 50% would receive high-intensity psychological interventions. This was varied from 100% receiving self-help (sensitivity analysis 2a) to 100% receiving high-intensity psychological interventions (sensitivity analysis 2b).
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Later identification – The basecase analysis assumed that for false negatives, around 10% would be diagnosed later during the time horizon. This was adjusted to 5% (sensitivity analysis 3a) and 20% (sensitivity analysis 3b).
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Reduction in quality of life in false positives – The basecase analysis assumed that quality of life was not affected by being a false positive. However, this was adjusted to assume a 2% reduction in quality of life, in line with previous models (sensitivity analysis 4) [17].
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Utility for depressed and non-depressed states – Estimates of utility for depressed and non-depressed states came from published literature [25]. However, to test the impact of the utility values, we adjusted the utility for depressed groups by increasing (sensitivity analysis 5a) and decreasing (sensitivity analysis 5b) the utility for ante-natal and postnatal depressed states by 15%.
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Resource use by false positives – False positives were assumed to use 20% of the resources for treatment. This was adjusted to 10% (sensitivity analysis 6a) and 30% (sensitivity analysis 6b) in sensitivity analyses.
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Spontaneous recovery in the model was taken from a summary of studies reported by Dennis et al. [29] The methods of these studies somewhat limit the applicability here (including small sample sizes, based in different countries, post-partum rather than ante-natal populations and being dated). Therefore, we varied the spontaneous recovery rate to 0% (sensitivity analysis 7a) and 50% (sensitivity analysis 7b) in sensitivity analyses.
Probabilities | Probability | Source | Data type | 95% CI | Distribution | Notes |
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No-screen positive | 0.2500 | Mitchell et al., 2009 [31] | Binomial | 0.171–0.339 | Beta | |
No-screen negative | 0.7500 | Mitchell et al., 2009 [31] | Binomial | 0.661–0.829 | Beta | |
No-screen positive - true positive | 0.4000 | Mitchell et al., 2009 [31] | Binomial | 0.221–0.594 | Beta | |
No-screen positive - false positive | 0.6000 | Mitchell et al., 2009 [31] | Binomial | 0.406–0.779 | Beta | |
No-screen negative - true negative | 0.8667 | Mitchell et al., 2009 [31] | Binomial | 0.782–0.933 | Beta | |
No-screen negative - false negative | 0.1333 | Mitchell et al., 2009 [31] | Binomial | 0.067–0.218 | Beta | |
Costs
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Cost (£)
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Source
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Data type
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95% CI
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Standard error
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Notes
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No-screen | 31 | Curtis & Burns, 2016 [49] | Assumed fixed | 12.77–49.23 | Assumed to be 30% | One GP appointment lasting 9.22 minutes, including direct care staff, no qualifications. |
Results
Screening approach | Mean QALYs | Mean Costs (£) | Incremental QALYs compared to no screen | Incremental costs compared to no screen | ICER compared to no screen |
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EPDS | 0.7304 | 1799 | 0.0049 | 34 | 6939 |
Whooley | 0.7302 | 1772 | 0.0047 | 7 | 1489 |
Whooley-EPDS | 0.7301 | 1748 | 0.0046 | −17 | −3696 |