The value of the TB-STS

The sub-themes of the value of the TB-STS that emerged from the interviews are shown in Figure 36.

117 Figure 36 – Sub-themes of ‘Value’

The value of the cluster report and cluster investigator

The cluster reports were valued by some HPUs because they lightened their workload by providing them with the summary information that they needed to know and recommending actions for certain clusters. This means that the HPUs did not have to look too closely at the strain typing reports themselves or monitor the strain typing locally. This was valued by HPUs, especially in low TB incidence areas where TB was not a high priority.

“[Cluster reports] recommended local cluster investigations which is very helpful because when you’re faced with growing numbers of cases and clusters it is useful to know where to focus your attention.” (CCDC, Low TB incidence)

“[The CI] sends cluster reports…saves us the effort of going through the [local] database.” (CCDC, Medium TB incidence)

The additional information held on the cluster reports can lead to more targeted investigations by the HPU. It was reported particularly helpful in situations where it was difficult to get information from patients as it provided nurses with specific lines of inquiry, rather than more general questioning that elicits an equally vague

118 response. On the other hand, one HPU argued that the information stored on the ETS was not detailed enough to make a recommendation about whether the cluster should be investigated, and that the decisions about clusters should be led locally where the local intelligence is held.

“We found it very useful because I didn't know the other cases associated with [the cluster]…so when we get these additional pieces of information it helps the TB nurses go back and ask specific questions - especially where there are language barriers and problems engaging with the patients.” (CCDC, Low TB incidence)

“Sometimes the summary is useful as we are armed with a few extra questions or directions.” (CCDC, High TB incidence)

Some HPUs were already aware of the cases in a cluster and their epidemiological links so the reports did not add any additional information and, therefore, did not lead to any public health action. For some it was seen as reassuring when the strain typing information confirmed what they already knew, whereas others felt that the cluster reports were not valuable. This may be explained by the timeliness that cases appear in cluster reports.

One of the main criticisms of the cluster reports was that they were not timely. Many HPUs found that by the time the cluster report arrived they had already completed their local investigation and contact screening activities, leaving no opportunity for the cluster information to influence public health activity. As a result the cluster report did not add anything to local TB control. In fact, some HPUs said that they referred to the laboratories directly for individual strain typing information where they suspected transmission because it was much quicker than waiting for the cluster reports.

“We do more action even before we receive the cluster report. It’s not too late, but definitely not timely to take public health action. We could do with

119 a bit more real-time reporting…then we could do away with our local

register.” (CCDC, Low TB incidence)

“By the time we get the report we already know about it and have carried out actions. It’s always too late… [the service] is not generating new information apart from the typing.” (Senior Health Protection Specialist, Medium TB incidence)

“If we have a feeling about cases then that would be very much in real time so you’d then request it and it would be on diagnosis, rather than a year or two down the line. We would do that anyway. We quite often request the VNTR for a patient and wouldn’t necessarily check the cluster information because it is easier and quicker to ask for the VNTR [from the

laboratories].” (Nurse Specialist, High TB incidence)

Another criticism of the cluster reports was that they often contained erroneous information or cases that were not from that HPU. This created additional, often unnecessary, work for the HPU and the TB nurses which wasted time, caused confusion, and people lost their confidence in the data. This problem was mainly associated with clusters that were both local and national as the information sharing systems between the local and national clusters was not very robust.

“It is a muddle when it is a national cluster - sometimes we are asked about patients that aren't even in our area. That has happened a couple of times. Not sure how robust the system is that someone in another part of the country will be identified as part of a cluster - don't feel very confident about that.” (Lead Practitioner Health Protection Nurse, Low TB incidence)

In general, however, HPUs enjoyed being able to see how the TB in their area fits into the wider picture and appreciate learning about regional and national clusters. The cluster investigators provided an important advisory role to the HPUs who struggled with the increasing workload and helped them to prioritise the clusters where an investigation may have led to public health action.

120 “I value the opinions and guidance and expertise and knowledge about -

they know what is going on and what people are doing in other areas. It is useful to have their advice…draw from other experiences.” (Health

Protection Nurse and TB Lead, Low TB incidence)

How the strain typing is used

Strain typing was mainly used to confirm or refute suspected transmission. Where suspected transmission was confirmed with strain typing it could be used to justify the time and resources then spent on managing complex TB cases, as well as justifying the actions taken. The ability to rule out suspected transmission changed the way that some HPUs managed their incidents, and the strain typing had become part of their decision-making process. However, where transmission was suspected in a particularly high risk setting, HPUs would request the strain typing directly from the laboratory so that transmission could be confirmed or ruled out quickly. In these circumstances the role of the cluster reports was diminished.

“Useful both in highlighting potentially linked cases we may not have thought of and disproving cases that might have been linked. There is a definite value in that.” (Senior Nurse Specialist and Regional TB Lead, Low TB incidence)

“Most of the benefits from strain typing has been where we started off before all of this - to confirm or refute epidemiological links.” (CCDC, Medium TB incidence)

Only a few HPUs reported using strain typing to identify potential new links between cases. This was the more conventional activity around a cluster investigation, requiring more time and resources and often resulted in a lot of effort but no newly identified links.

“There is implications for it because it tells us to throw the net wider or to stop. Sometimes it makes the work more, and no real outcome, but it does help – another reassurance mechanism. Gives us a justification for what we're doing.” (CCDC, High TB incidence)

121 The strain typing was reported to be particularly useful for on-going outbreaks as it helped to define a case in an outbreak (where the case is culture positive) so one could learn early on about new cases and this could influence the contact tracing strategy and allow for targeted contact tracing as early as possible. Where cases were reluctant to disclose their contacts, strain typing could help to identify relationships with other cases and helped the nurses tailor their interviews with patients.

Some HPUs found the strain typing useful for monitoring and evaluation. Where additional cases were identified with the same strain type and they were linked epidemiologically to another case in the cluster it suggested that the contact tracing was not as thorough as it should have been, or where no more cases were added to the strain typing cluster one could be certain that the contact tracing was carried out well. One HPU has even used the strain typing to argue for more resources for TB so that contact tracing could be carried out more thoroughly.

Added value

The ability to see the bigger picture of TB was identified as an added value of the TB-STS. HPUs were focussed on their own geographical area and the strain typing provided information about how they fit into the national context. However, according to the HPU staff interviewed from areas of low, medium and high TB incidence, in terms of public health output the TB-STS had not yet delivered. Many people, especially in high TB incidence areas, felt that the TB-STS generated more work that led to little benefit.

“Hasn't added benefits so far, but hasn't highlighted anything we weren't already dealing with...Very happy to receive the strain typing - wouldn’t want to not receive it.” (CCDC, Medium TB incidence)

“My gut feeling is that they are perhaps not the most efficient use of scarce resources. I haven't seen anything arising out of these investigations that's actually made a difference in terms of public health management, and yet

122 there is a lot of traffic of questionnaires being distributed from Colindale to

TB nurses.” (CCDC, Medium TB incidence)

“Haven't done anything so far that has led to us being able to target wider screening or to feel like we’ve taken a public health action that wouldn't already have been taken. We haven't delivered anything on the back of it.” (CCDC, High TB incidence)

The TB-STS added value in other more general ways that strengthened the TB service as a whole. It helped to engage TB nurses with the public health aspects of TB and developed their relationship with HPUs. On the other hand, the increased demand placed on TB nurses to gather additional information and complete more forms put pressure on this relationship in some areas. This pressure, however, resulted in TB nurses in some areas collecting the data in the cluster questionnaires prospectively for each case, rather than retrospectively and this was recognised as a main benefit of the service so far.

“It's a good thing. It's been helpful for us. It's a good way of getting people more interested in more work around TB. Doing cluster investigations has been a good way also of building up relations with the nurses. They now ring us to ask about strain typing. It has improved dialogue.” (CCDC and Regional TB Lead, Medium TB incidence)

Many HPUs saw the potential future value of the TB-STS and acknowledged that the service was still new and that, as more data are collected and analysed, more could be learned from it.

Despite the lack of outcomes and drain on resources, people felt that it would be regressive to stop strain typing.

“From a clinical viewpoint the effects are marginal. Would I keep the cluster work that's being done? Yes, I probably would. Would I fund it out of my budget? Probably not.” (CCDC, Medium TB incidence)

123 “The general strain typing is like a fishing expedition.” (CCDC, Low TB

incidence)