Mobile X-ray outside the Hospital: a review CURRENT STATUS: UNDER REVIEW

Background For several years mobile X-ray equipment has been used in intensive care units, when transportation to the radiology department was inadvisable. Now, mobile X-ray examinations are also used outside hospital. The literature describes that fragile patients may benefit from mobile X-ray, but we need to know if it is an evident alternative to hospital-based examination and in what populations. Methods We searched PubMed, Cinahl and Embase for English-, Danish-, Norwegian - and Swedish-language studies, published within the last 10 years about mobile X-ray outside the hospital. We decided that both qualitative and quantitative studies were eligible. Result We included nine studies in this scoping review. The results were divided into four topics : 1. Target population 2. Population health 3 . Experience of care and 4. C ost effectiveness . The conclusions are unclear, as quality of the evidence is low, the study populations are small, and the descriptions of the technology are week. Conclusion Mobile X-ray may be used outside hospital. There seems to be potential benefits to both patients and health care staff. Based on the published studies it is not possible to conclude if mobile X-ray examination is a relevant diagnostic offer and for whom. Further studies are needed to assess the feasibility of use in fragile patients, also regarding staff, relatives and society.


Abstract
Background For several years mobile X-ray equipment has been used in intensive care units, when transportation to the radiology department was inadvisable. Now, mobile X-ray examinations are also used outside hospital. The literature describes that fragile patients may benefit from mobile X-ray, but we need to know if it is an evident alternative to hospital-based examination and in what populations.
Methods We searched PubMed, Cinahl and Embase for English-, Danish-, Norwegian -and Swedishlanguage studies, published within the last 10 years about mobile X-ray outside the hospital. We decided that both qualitative and quantitative studies were eligible. Result We included nine studies in this scoping review. The results were divided into four topics : 1. Target population 2. Population health 3 . Experience of care and 4. C ost effectiveness . The conclusions are unclear, as quality of the evidence is low, the study populations are small, and the descriptions of the technology are week.
Conclusion Mobile X-ray may be used outside hospital. There seems to be potential benefits to both patients and health care staff. Based on the published studies it is not possible to conclude if mobile X-ray examination is a relevant diagnostic offer and for whom. Further studies are needed to assess the feasibility of use in fragile patients, also regarding staff, relatives and society.

Background
For several years mobile X-ray has been used in intensive care units for making diagnostic decisions (1). Still it is used, when patients are too fragile to be transported to the radiology department (2)(3)(4).
In fragile patients e.g. nursing home residents, the environmental change from home to hospital for examination may result in delirium. The patients experience disease deterioration, a need for increased care and medication for several days after the admission to the hospital (4)(5)(6)(7). In fragile patients, examination at the hospital can be a challenge due to transport to the hospital, long waiting times, and a need to be accompanied. These patients also require extra care before, during and after the examination (7). A review published in 2017 indicated that mobile X-ray for nursing home residents in the Western world are of comparable quality to X-ray examinations at the hospital and have potential benefits as mobile X-ray reduced transfers to and from hospital, increased the number of examinations carried out, and facilitated timely diagnosis and access to treatments. But they concluded that further research was needed to evaluate potential improvements in care quality and cost-effectiveness. Furthermore, the study population only included nursing home residents (8).
Our aim of this scoping review was to disclose published knowledge about the use of mobile X-ray.
For that reason, we asked four study questions: Using mobile X-ray

1.
What is the target patient population?

2.
What are the improvements of population health?

3.
What are the experiences of care?

4.
Is mobile X-ray a cost-effective intervention compared to X-ray at hospital?

Method
A literature search and review. We chose to conduct a narrow systematic review due to the limited number of studies.

Literature search
The following databases were searched: PubMed, Cinahl and Embase. publications that fulfilled our criteria. In figure 1 an overview of the included and excluded studies and reasons for exclusion is presented. In a supplementary search about image quality we identified 246 records, of which we ended up with 4 full text articles already found in the first literature search. "diagnostic" AND (x radiography* OR x ray* OR radiotherap* ) 3 mobile AND ("radiography" OR x ray* OR radiotherapy*) 4 transportable AND ("radiography" OR x ray OR radiotherapy*) 5 Portable AND ("radiography" OR x ray* OR radiotherapy*) 6 "X-rays" [Mesh] 7 "Nursing Homes" [Mesh] 8 "Homes for the Aged" [Mesh] 9 "nursing" AND ("home" OR "homes" OR facilit*) 10 "home for the aged" OR "home for the elderly" OR "homes for the aged" OR "homes for the elderly" 11 ((intermediate

Selection of records and methodological quality appraisal
The records were archived and assessed using the computer program 'Covidence'. In Covidence when screening the literature, in the selection you choose between 'yes', 'no' and 'maybe'. All literature selected as 'yes' and 'maybe' was double-checked by Co-author CPN.

Data extraction and synthesis:
To extract data from the selected articles, we were inspired by Peters to use a structured summary table (12).

Inclusion criteria
Study design: Randomized controlled trials, non-randomized trials, cohort studies, case-control studies, cross -sectional studies, case reports and series.
Countries: Western countries, USA and Europe. We only considered these countries as comparable concerning X-ray equipment, patient facilities, transporting, environment, nursing staff and the purpose of using mobile X-ray.
Time period: The last 10 years. This period was chosen because X-ray equipment older than 10 years is normally not used.
Language: Abstracts and/or articles published in the English, Danish, Norwegian, and Swedish languages.

Exclusion criteria
Study design: Ideas, editorials, personal opinions, letters, study plans, newspaper articles, protocols, posters, animal research studies, reviews and metaanalyses.
Intervention: Mobile X-ray used in a hospital setting.

Results
The literature search resulted in 9 included studies (table 1). We find that there are several limitations related to the included literature, probably due to the character of the field. A few of the included studies are randomized, while the rest is non-randomized, not ranging high in the evidence hierarchy.
The studies do not have many participants and some of the studies are based on opinions and predictions. Therefore, the quality and the results of the studies are limited.
Mobile X-ray was compared to hospital X-ray in all studies. The interventions were mobile X-ray (13)(14)(15)(16)(17)(18)(19)(20) and mobile X-ray combined with hospital X-ray (21). The most common X-ray examinations were of chest, hip and pelvis, spine and abdomen, but not all studies included all the mentioned examinations. Some studies only included chest X-rays (15,17).
The literature describes several different qualitative and quantitative methods to measure outcomes such as population health, experience of care, quality and costs (13)(14)(15)(16)(17)(18)(19)(20)(21). The quality of the studies differs a lot and there is no agreement on the appropriate outcome measures. The quality of the studies is low and may be biased. To define specific outcomes of mobile X-ray, a specific target population is needed.

Target patient population
The study populations in the literature were frail elderly, homeless, drug users, asylum seekers, and nursing home residents (13)(14)(15)(16)(17)(18)(19)(20)(21). We do not know, if the included target population in the literature benefits from mobile X-ray and therefore this target population may be too large. The problem is also, that the target population might differ in each country and therefore it may not be possible to define a specific target population for mobile X-ray in general. But this does not mean that mobile X-ray could not be used in other locations than described in the literature, e.g. at the local general practitioner (GP), in a healthcare center in order to meet the ambulant patient's needs, but also the needs of the health care staffs, crowded hospitals and general practitioners. We do not know if the locations described are the right locations. It may differ in each country.

Improving population health
Improvements of population health are measured by several different outcomes that by proxy may indicate if health status is improved. The outcomes were delirium measured by confusion assessment method, sensitivity and specificity of mobile X-ray to find tuberculosis, patient and health care satisfaction measured by qualitative interviews and questionnaires, image quality and costs (13)(14)(15)(16)(17)(18)(19)(20)(21).The outcomes of the studies describing improved population health give a mixed and unclear indication of what to be used as outcome measures.
The literature suggests that mobile X-ray seems to increase the certainty of presumed diagnoses so that treatment could be avoided in many cases (15)(16)(17)20). Examination using mobile X-ray could also prevent patients from being treated at the hospital. Fewer patients may need transportation to the hospital, and probably fewer patients would become delirious (15)(16)(17)20). The literature also describes places to use mobile X-ray outside the hospital for instance in nursing homes and shelters (13)(14)(15)(16)(17)(18)(19)(20)(21).
For nursing home residents that may suffer from pneumonia, mobile X-ray was considered a reasonable alternative to hospital X-ray examination. Patients with chest pathology could be treated at home. This reduced the incidence of delirium (15)(16)(17)20). Also, less transfer to the hospital is a positive outcome, since transportation of patients from their homes to the hospital may worsen the condition of demented or disorientated patients.
The negative consequences of the transfer may result in residents not being examined or hospitalized. Examination in the familiar surroundings may calm down the patients, as insecurity during transportation to hospital is experienced as pain or confusion (16)(17)(18)20,21).
The included studies both use qualitative, quantitative, evidence-based outcome measures and non-evidence based methods. Proper outcome measures remain to be established.

Experience of care
The five included studies explored the quality, usefulness, knowledge, and expectations of mobile Xray offered to nursing home residents. Patients, healthcare staff, nurses and referring doctors were asked using both qualitative and quantitative methods (15,17,(19)(20)(21).
The literature found that the main part of patients and health care staff was satisfied with mobile Xray examination and the benefits that mobile X-ray had for both patients and staff (15,17,(19)(20)(21).
Results showed high patient acceptance of mobile X-ray. The patients were happy not having to go away for several hours, felt safe and that it was much better than going to the hospital for examination. No patients had a negative opinion of the procedure. Nursing home staffs pointed out beneficial factors such as the security and comfort for the patients who could remain in their usual environment, no need for transportation, and no need for staff to be absent from the nursing homes while accompanying the patient to the hospital (15,17,20).
But the question is if the quality of the studies permits making conclusions concerning experience of care. No studies measured satisfaction in a randomized controlled trial. We did not find two studies measuring experience of care using the same outcome measures in an identical population. We found, that the target population for measuring experience of care could also be other groups than the patients and health care staff in the studies. For instance GP, heads of departments, relatives or other persons involved in mobile X-ray.
The literature shows that mobile X-ray may facilitate high quality of treatment and care. At the same time it was pointed out, that the diagnostic quality of the images may be a challenge, since the health care staff may have to choose between good enough image quality with no transportation of patients and optimal image quality with transport. Also, there was no consensus of how to measure the diagnostic image quality (15)(16)(17)19,21).
When asking the referring doctors if the mobile X-ray examination had given important information to patients and their families, they replied positively (15,17,20).
The literature shows that measuring experience of care is difficult and it may be the reason why no one has documented a gold standard for doing that. We find that it is difficult because the patients are fragile and therefore, they are probably not able to share their experiences of mobile X-ray.
Information from referring doctors, healthcare staff, and relatives may be biased and not representing patients' views.

Cost effectiveness
We found no study measuring cost effectiveness. To conclude if mobile X-ray is cost efficient, all possible measurable costs of both mobile X-ray and X-ray at the hospital must be compared in an economic evaluation with clear outcome measures.
The literature describes that mobile X-ray is cost effective compared to X-ray at the hospital, but this is not supported by evidence. No studies compare cost effectiveness between mobile X-ray and X-ray at the hospital. The studies investigate costs such as cost per patient, salary, capital costs of equipment and facilities, and operating costs. It is only possible to suggest that the cost is probably lower using mobile X-ray seen in a very narrow perspective not including derived costs (15,19,21).
Many patients would not have been examined, had mobile X-ray service not existed (20).

Discussion
The purpose of this review was to identify published knowledge in the Western world within the last 10 years about mobile X-ray examination outside the hospital compared to examination at the hospital. We wanted to find out if mobile X-ray is an effective alternative to X-ray at the hospital and for whom.
By conducting the literature review we hoped to find results that could show which study design and outcome measures we should use to document the effect of mobile X-ray.
It was surprising that only 9 studies could be included in the review, but when reading the studies, we found that mobile X-ray is a difficult topic with many aspects to consider when defining target population and measuring effects such as population health, experience of care and costs.
Overall, the target population seemed to be fragile patients, who benefit most of avoiding transportation to the hospital. Nursing home residents, frail elderly, homeless, drug users and asylum seekers were included in the studies. In our opinion other patient groups may also be included or at least studied as possible target populations, e.g. hospice patients for palliative care, group dwelling for people with intellectual disabilities, psychiatric patients, and patients in other relevant institutions could be target populations. In defining the target population country and environment, specific factors may also influence the definition of the relevant target population. Consequences of transportation, environmental changes or waiting time for the patient are not clear.
Another problem is measuring the effect of mobile X-ray. Nine studies have applied the study design they considered most suited for measuring the effect of mobile X-ray. The outcomes were as described delirium, sensitivity and specificity of mobile X-ray to find tuberculosis, patient and health care satisfaction measured by qualitative interviews and questionnaires, image quality and costs.
They all conclude that further studies are needed to measure the effect, but at the same time they found that mobile X-ray probably benefits the patient in different ways. The problem is that one outcome measure may be relevant for one patient group but not for all patient groups. For demented patients measuring delirium could be a relevant outcome measure, for a homeless, sensitivity and specificity of detecting tuberculosis are more relevant.
Another challenge is also measuring experience of care. The included patient and healthcare staff seem to be satisfied with mobile X-ray. But experience of care and satisfaction may not be comparable between different patient populations and different health care staffs. When asking a demented nursing home resident, relatives or health care staff about their satisfaction with mobile Xray, no transportation or preventing the possible effects of delirium could be related to high satisfaction. Asking homeless residents or asylum seekers about satisfaction, these outcome measures probably would not even be relevant.
A problem in the included studies is that no one evaluated images in a randomized controlled trial comparing quality of mobile X-ray images to X-ray images at the hospital. When offering a hospital based examination outside the hospital, it is important to be able to document the quality of the treatment.
MDT conducted the literature search, designed the review protocol and search strategy, conducted the literature retrieval, reviewed all abstracts identified, read all potentially relevant articles, scored all articles included in the review, and wrote the initial draft of the paper. EMSD and CPN reviewed all abstracts identified, read all potentially relevant articles, scored all articles included in the review, and contributed to and edited the paper. FM and TEMC contributed to and edited the paper.