THE NHS Scotland staff survey comes with an obvious caveat.

We know such internal polling exercises can produce negative responses. Their very existence is, in part, to provide an outlet for frustrations and an open invitation to air concerns.

Nevertheless, the latest snapshot of opinion in our health service is alarming. This is partly because its publication allows us to make comparisons with the last year the survey was carried out. The same questions were asked in 2010, in many cases with identical wording.

So the fact that only 55% of NHS workers are convinced the care of patients is their board's top priority is shocking. It is also substantially lower than the proportion three years ago - 63% - who felt patients were their board's main concern.

If nurses and midwives only are counted, that figure falls further to 45%. Meanwhile, fewer than a quarter of nurses believe staffing levels permit them to do their job properly.

The figures mirror a recent survey by the Royal College of Nursing (RCN) which found 54% of nurses were having to work beyond their contracted hours on a weekly basis - essentially working for free to ensure patients' needs are met. A majority were unhappy at their ability to do their jobs effectively.

RCN Scotland Director Theresa Fyffe says the new figures are a "damning indictment" of the Government's goal of making the NHS a world class patient-centred organisation.

That is maybe overstating the case. Certainly some of these figures seem to be going in the wrong direction. But the NHS in Scotland has had protection from budget cuts and is in considerably better shape than its counterpart south of the border.

The lessons from England and Wales are that if we want that to continue, we must remain vigilant.

In particular it is crucial staff feel safe to raise concerns - to speak up when things have gone wrong and to speak out about problems, even if it means criticising a superior. On this issue, the survey had better news, with 52% of staff saying they would be willing to challenge the way things are done, the first time more than half of staff have responded in this way.

Of 20 statements about attitudes to the NHS, their work and their personal satisfaction, staff answered more negatively than in 2010 to all but two. Researchers say this may reflect "an overall dip in employee satisfaction."

Yet much would improve if staff simply felt valued.

Minister for Health Michael Matheson insist the Government will act on the survey results.

Concerns about under-staffing must be taken seriously, despite recent figures showing NHS staffing has risen. But other staff concerns should also be heeded. It is notable one of the survey's findings is that staff have not felt informed about board decisions or felt involved when changes are made.

These important insights into the real experiences of frontline workers will only have value if staff feel they have a say year-round, and that boards are committed to real change, and in patients' best interests.